Part 17

=The physiological, experimental investigation= of the functions of the bone-marrow offers insurmountable difficulties. An exclusion of the whole bone-marrow or of larger portions only is an impossible operation. Nor can we ascribe any value to the researches which endeavour to obtain a result by comparative enumerations of the arterial and venous blood of a bone-marrow area. J. P. Roietzky working under Uskoff's direction has recently made counts of this kind in the dog, from the nutrient artery of the tibia and the corresponding vein. He found that the number of white corpuscles of the vein is slightly greater, that on the other hand the absolute number of "young corpuscles" (Uskoff), i.e. of the lymphocytes, has been considerably diminished, whilst the number of "ripe" corpuscles, which for the most part correspond to our polynuclear, is considerably increased. He gives the following table:

------------------------------------------------------------- Total number | Young | Ripe | Old | corpuscles | corpuscles | corpuscles ------------------------------------------------------------- Arterial blood 15000| 1950 (13%) | 840 (5.6%) | 12210 (81%) Venous " 16400| 656 (4.0%)| 2788 (17.0%)| 12956 (79.0%)

The argument based on figures such as these assumes that the function of the bone-marrow is =continuous=; an assumption which Uskoff indeed seems to make.

But if the bone-marrow is constantly absorbing the lymphocytes to such an extent, it is quite incomprehensible how the normal condition of the blood can be preserved, bearing in mind the extent of the bone-marrow and the rate of the circulation. All evidence indeed tends to shew that on the contrary the bone-marrow performs its functions discontinuously, inasmuch as elements continually grow to maturity in the bone-marrow, as we have above explained, but they only emigrate at certain times as the result of chemical stimuli. It is obvious à priori from this consideration how inconclusive must be the results of experiments such as these of Roietzky.

Far more important for the elucidation of the function of the bone-marrow are =clinical observations= on cases in which considerable portions of the bone-marrow are replaced by tissue of another kind. We may best divide the observations on this point into two groups: 1. malignant tumours of the bone-marrow, 2. the so-called acute leukæmia.

There are unfortunately very few available observations as yet upon the first group. Still rarer are the cases in which as is necessary the whole bone-marrow has been subjected to an exhaustive examination, which alone affords adequate evidence of the extent of the defect.

Amongst the changes of the bone-marrow arising from tumours one may distinguish two groups, according to the nature of the condition of the blood. The first type is exemplified by a case of Nothnagel published in his work on lymphadenia ossium. Here during life the blood shewed, in the main, the features of a simple severe anæmia; but in addition isolated normoblasts, small marrow cells, and moderate leucocytosis. The autopsy, at which the whole skeletal system was subjected systematically to an exact examination, shewed a complete atrophy of the bone-marrow, and replacement of the same by the tumour masses. In this case then the condition of the blood in vivo is satisfactorily explained by the absence of function of bone-marrow. Nothnagel conjectured that the formation of the scanty nucleated red blood corpuscles occurred vicariously in the spleen, that of the leucocytes in the lymph glands.

In the second series to which the cases of Israel and Leyden, as well as the recently published one of J. Epstein from Neusser's wards, belong, the blood shews, besides the usual anæmic changes, other anomalies which are peculiar partly to pernicious anæmia, partly to myelogenic leukæmia. In Epstein's case of metastatic carcinoma of the bone-marrow, there was found a considerable anæmia, with numerous nucleated red blood corpuscles both of the normo- and megaloblastic type; their nuclei presented the strangest shapes, due not merely to typical nuclear division, but also to nuclear degeneration. The white blood corpuscles were much increased, their proportion to the red was 1/25 to 1/40; the increase concerned in the main the large mononuclear forms, which bore for the most part neutrophil granulation, and were therefore to be called myelocytes. In all the specimens, only two eosinophil cells were found.

The explanation of a blood picture of this kind, apart from the purely anæmic changes, is by no means easy, as Epstein rightly observes. The appearance of myelocytes is most readily explained by a direct stimulation of the remaining bone-marrow by the surrounding masses of tumour. In this, the mechanical factor is less concerned than the chemical metabolic products of the tumour masses; which at first act on the adjacent tissue in specially strong concentration, and also in a negatively chemiotactic manner on the wandering cells. This view receives support from the careful work of Reinbach on the behaviour of the leucocytes in malignant tumours. Out of 40 cases examined, in only one, of lymphosarcoma complicated with tuberculosis, were myelocytes found in the blood, amounting to about 0.5-1.0% of the white blood corpuscles. The autopsy shewed isolated yellowish white foci of growth in the bone-marrow, reaching the size of a sixpenny piece. Bearing in mind that in none of the other 39 cases were myelocytes demonstrated, one does not hesitate to explain their presence in the blood in this single case by the metastases in the bone-marrow. The small extent of the latter is likewise the cause of the small percentage of the myelocytes.

In explaining the presence of the megaloblasts in the blood of Epstein's patient we must keep before us what we have said elsewhere on this kind of cell. They are not present in the normal bone-marrow; they arise on the contrary, according to our view, when a specific morbid agent acts upon the bone-marrow, as we must assume is the case in the pernicious forms of anæmia. In the cases of anæmia from tumours, in which we find megaloblasts in large numbers in the blood, we must likewise assume that chemical stimuli proceed from the tumours, leading to the formation of megaloblasts in the bone-marrow.

The presence of megaloblasts in the bone-marrow does not itself cause their appearance in the blood, for in pernicious anæmia the bone-marrow may be filled with megaloblasts, and yet only very scanty examples are to be found in the blood. Whether the emigration of the megaloblasts from the bone-marrow into the blood-stream is in general to be referred to chemical stimuli, as it is in the particular case of Epstein's, or to mechanical causes, cannot at present be decided.

The bone-marrow may be replaced by typical lymphatic tissue, as well as by the substance of malignant tumours. The former occurs constantly in lymphatic leukæmia according to the well-known results of Neumann, which have since been generally confirmed. In these cases extensive tracts of bone-marrow are replaced not by masses of malignant growth but by an indifferent tissue, so to speak, a tissue which is unable to exercise the above-described stimulating influence upon the remaining bone-marrow. It is owing to this circumstance that we are able to observe in the cases of lymphatic degeneration of the bone-marrow the phenomena due to its exclusion, in their most uncomplicated form.

The most convincing results are obtained from cases of acute (lymphatic) leukæmia, the pretty frequent occurrence of which was first noticed by Epstein, and which has lately been very thoroughly studied by A. Fränkel. For the purpose in question, acute leukæmia is specially suited, since the abnormal growth of the lymphatic tissue takes place very rapidly, and for this reason brings about a quick and uncomplicated exclusion of the bone-marrow tissue; as it were, experimentally. Under its influence the neutrophil elements of the bone-marrow vanish rapidly, and in many cases so completely that it needs some trouble to find a single myelocyte, as for example in a case of Ehrlich's. The polynuclear leucocytes are produced in the bone-marrow, consequently where the bone-marrow is destroyed, as in this case, it is clear that their numbers must be absolutely very much diminished in the blood.

Dock has also arrived at similar results, as we see from a preliminary report; and he similarly explains the absence of neutrophil cells in lymphatic leukæmia by the replacement of the myeloid by lymphatic tissue.

Thus lymphatic leukæmia affords a striking proof that the lymphocytes are cells of a peculiar kind, and which are quite independent of the polynuclear cells. It is therefore exceedingly surprising that Fränkel, after accurately examining and analysing eight cases of acute lymphatic leukæmia, believes he has found in them imperative reasons for the assumption that the lymphocytes are transformed to polynuclear cells. This can only be explained by the confusion which Uskoff's doctrine of "young cells" has brought about.

We define lymphocytosis as an increase of the lymphocytes of the blood; Fränkel like Uskoff regards it as the emigration of the young forms of the white blood corpuscles into the blood. He concludes logically from the diminution of the polynuclear cells in this form of disease "that the conditions of the transformation of the young forms have undergone a disturbance." But if one assumes that the lymphocytes are young forms, and the polynuclears their older stages, it is much nearer to the facts to speak, not of a disturbance in lymphatic leukæmia, but of an absolute hinderance to the ripening process. It is easy to conceive any particular stimulus or injury bringing about an acceleration of the normal process, that is, a premature old age, but it is equally difficult to represent clearly to oneself conditions which retard or completely prevent the normal ageing of the elements. The discovery of such conditions would be really epoch-making, both for general biology, and for therapeutics. The only escape from this dilemma would be the assumption of a very premature death of the lymphocytes, for which however not the smallest evidence is to be found, even in Fränkel's monograph. Fränkel distinguishes the acute from the chronic forms of leukæmia by the fact, "that in the former the newly formed elements emigrate from their places of formation into the blood-stream with extraordinary rapidity. Hence there is not time for further local metamorphosis. In chronic leukæmia the emigration takes place very probably much more slowly." This distinction is contradicted by the facts; for =there are chronic forms of lymphatic leukæmia whose microscopic picture is identical with that of acute leukæmia=. And hence the starting-point of all Fränkel's deductions is rendered insecure.

FOOTNOTES:

C. S. Engel has recently proposed to call acute leucocytosis "=lienal leucocytosis=," in analogy with the clinical idea of a lienal leukæmia. This terminology should only be used if the polynuclear cells did in fact arise from the spleen, an assumption which Engel himself does not once appear to make, since he expressly warns against drawing any conclusions from this name as to their origin. Since, however, the acute leucocytoses, as we shall shew in the next section, are exclusively to be referred to the bone-marrow, the term lienal leucocytosis seems to us quite mistaken, for it must logically lead to a conception of the origin of the leucocytes, exactly opposed to their actual relationships.

Many authors, e.g. Arnold, explain this double staining of the eosinophil cells by the presence of eosinophil and mast cell granulation side by side. That this is certainly not the case is shewn by the fact that the "basophil" granulation of the eosinophil cells does not in metachromatic staining shew the metachromasia characteristic for the mast cells.

A. Fränkel has recently reported histological investigations in which he could demonstrate in one case true myelocytes in inflamed lymph glands. He says (xv. Congress f. innere Medecin): "For some time past I have had systematic examinations carried out by my assistant, Dr Japha, on the granulations of the leucocytes contained in these glands in a large number of infectious diseases, which are accompanied by acute swelling of the lymphatic glands, such as scarlet fever, diphtheria, typhoid. They were performed in the following way: dry cover-slip preparations were made from the juice of the glands removed shortly after death, and were stained in the usual way by Ehrlich's triacid mixture. Amongst a large number of cases thus examined, it was possible in only one case of scarlet fever--but in this beyond all doubt--to demonstrate the presence of mononuclear cells with neutrophil granulation." The extreme rarity of this condition supports our opinion that the formation of neutrophil mononuclear elements cannot be regarded as a normal function of the lymphatic glands. Polynuclear neutrophil cells are nearly always naturally present in inflamed lymph glands, as a product of the inflammation which has immigrated there. Every pus preparation shews that the polynuclear neutrophil leucocytes can change in the tissues to mononuclear, and the isolated observations of Japha should be explained in this manner.

Moreover the investigations of Roietzky are quite without foundation, inasmuch as the tibia of the dog, upon which this author performed his experiments, contains in all races of dogs--according to the information very kindly given us by Prof. Schütz--no red marrow, but fatty marrow only, which as is well known is incapable of the smallest hæmatopoietic function.

We draw particular attention to the small number of eosinophil cells, since according to Ehrlich's postulates this absence of eosinophil cells is incompatible with the diagnosis of a leukæmia.

In contrast to this lymphatic metamorphosis of the bone-marrow, in myelogenous leukæmia a myeloid transformation of the other blood-forming organs, especially of the lymph glands is found; a transformation sufficiently characterised as myeloid by the presence of myelocytes, eosinophils, and nucleated red blood corpuscles.

III. ON THE DEMONSTRATION OF THE CELL-GRANULES, AND THEIR SIGNIFICANCE.

During the last ten years a large amount of valuable work has been done on the cell-granules from histological, biological and clinical sides. This has particularly assisted hæmatology, where a number of problems remain whose solution is only possible by the aid of a knowledge of the granules. We must therefore consider the history, methods, and results of this work.

Ehrlich was undoubtedly the first to insist on the importance of the cell-granules, and to obtain practical results in this direction. We are obliged to mention this, since Altmann has, in spite of express corrections, repeatedly asserted the contrary. In 1891 Ehrlich refuted Altmann's claim to priority, nevertheless, Altmann in the 2nd edition of his Elementary Organisms (1894) stated that before him no one had recognised the specific importance of the granules, though some authors had viewed them as "rare and isolated phenomena."

We may quote a passage published by Ehrlich in 1878, that is, ten years before Altmann's papers. "Since the beginning of histology the word 'granular' has been used to describe the character of cellular forms. This term is not a very happy one, since many circumstances produce a granular appearance of the protoplasm. Modern work has shewn that many cells, formerly described as granular, owe this appearance to a reticular protoplasmic framework. And we have no more right to call cells granular in which proteid precipitates occur, either spontaneously as in coagulation, or from reagents (alcohol). The name should be kept exclusively for cells in which during life substances, chemically distinct from normal proteid, are embedded in a granular form. We can readily distinguish but few of these substances, such as fat and pigment; most of them we can at present characterise but imperfectly, or not at all."

"Earlier observations, especially on the mast cells, led me to expect that these granulations, though they had long been inaccessible to chemical analysis, could be distinguished by their behaviour with certain stains. I found, in fact, granules of this kind, characterised by their affinity for certain dyes, and which could thereby be easily followed through the animal series and in various organs. I further found that certain granules only occurred in particular cells, for which they were characteristic, as pigment is for pigment cells, and glycogen for cartilage cells (Neumann) and so forth. We can diagnose the variously shaped mast cells only by the staining of their granules in dahlia solution, that is by a microchemical test. And in the same way we can separate tinctorially other granulated cells, morphologically indistinguishable, into definite sub-groups. And for this reason, I propose to call these granulations =specific=."