Part 22

These aerial spiders are of two sizes, although of the same colour and general appearance; they are probably male and female. At all events they do not vary in size more than other species of spiders when the sexes differ.

Has it been observed by naturalists that spiders eat their own webs? A large one that I used to feed when I was a lad with wasps, humble bees, and flesh-flies, used to do so occasionally. These insects were so strong that they often ruined the web in their efforts to escape, and the spider, quite aware of the rough customers it had to deal with, would often coil a cable of many folds round them before venturing to seize them with its mandibles. It would, if the web was ruined by the struggles of the insect, deliberately gorge it, which I accounted for by supposing that unless it did so it would not be able to secrete a sufficient supply of material to enable it to spin another.

The leaping spiders are another curious species, which construct no webs, although they spin threads. This spider may be seen frequently on the walls of houses, and if carefully watched it will be seen to range up and down in quest of small gnats and other insects; when it observes one it creeps to within about two inches of it, and backing slightly, it appears to hesitate for a moment, and then springs upon the fly, but always before doing so it fixes a thread to the spot from whence it springs, so that if the fly happens to be too strong for it, and is able to detach itself from the wall, they both remain suspended from the thread which has been previously fixed by the spider. This I have seen more than once.

They sometimes venture on larger game than the small gnats. One I was watching one day came upon one of the large Ephemera (the Browndrake), an insect ten times as large as the spider, but after many points (for the setting of the spider before it springs is very similar in manner to that of a thoroughbred pointer ), in which it kept varying its position, apparently to gain some advantage, it gave up the attempt, discretion proving the better part of valour.

When botanizing on Erris Begh (in Connemara), this summer, I passed through many spider-lines so strong as to offer a very sensible resistance before breaking. I don't remember to have ever before met with them so strong and tenacious, and the makers of optical instruments might there have found abundance of threads which I am told are valuable as cross-wires for transit- instruments and theodolites. I did not meet with any of the spiders that had thrown out these lines, but judging of them by their works I suppose they must have been large ones.

One of your correspondents was inquiring a few weeks since how it was that a spider could throw out a long line between two trees or buildings at a considerable distance from each other. This seems to me to be very easily explained, if we reason from the analogy of the flying spider. The spider seems to throw out a line, trusting it will catch somewhere or other, and it is able to ascertain it has done so by pulling at it, and when it finds that it is firmly fixed it starts off to travel upon it, as I have occasionally noticed.

Everyone has noticed how carefully the spider carries her cocoon of eggs attached to the vent, and how disconsolate she appears to be when deprived of them; but I don't think it is so generally known that some of the spiders carry their young on their backs for some time after they are hatched. I remember seeing an instance of this one day when on the Moors, grouse-shooting. I saw what seemed to be a very curious insect travelling on the ling (heather), and on stooping down to examine it I found it was a large spider, upon the back of which (in fact, all over it) were clustered some dozens of young ones, about the size of pins' heads; she also seemed to guard them with great care, and seemed much afraid of losing them.

FINIS.

NOTES.

There is a fish somewhat resembling the Brambling in the Dunsop, a tributary of the Hodder, where it is known by the name of the Bull Penk.

My opinion that neither Trout nor Salmon spawn every year is I think strongly corroborated by the fact, that previous to the Act of 1861 the London fish market was supplied with Salmon of the largest size, and of the best quality, in October, November, and December. When these fish were examined, it was found that the ovaries were but small, and the individual ova were not larger than mustard seed. These fish could not have spawned that season, nor would they have done so if left alive, if the growth of the ova in the ovaries is uniform--I mean if the growth of the ova is as great in one month as another--because in May and June the ova in a female Salmon is four times as large as these were in November.

Again, when the gas tank at Settle was emptied into the Ribble, in September, 1861, all the fish so far as was known were killed between that place and Mitton, Salmon as well as Par and Trout. Supposing that Salmon spawn every year, and that the Smolts come up the river, as Grilse in the summer of the same year in which they have gone to the sea in the spring, there ought to have been a great scarcity of both Grilse and Salmon in the Ribble in the year 1862, but so far was this from being the case, that both Grilse and Salmon were more abundant that season than they had been for some years previously, but there was a scarcity of both in 1863.

Again, when the Smolts were turned out of the breeding ponds at Dohulla, Galway, the experiment was looked upon as a failure because no Grilse returned the same season, not one having showed itself, but many came the summer after, proving pretty conclusively that in some rivers, at all events, the Smolt requires a year's residence in the sea before it returns as Grilse.

In the evidence of Mr. George Hogarth, it is stated that he saw upwards of ninety Kelt fish in the mill lead at Grandholme, on the Don, May 6th.

Salmon are said to produce 18,000 or 20,000 eggs each, and I have no doubt that a large Salmon will produce more, as one I examined a year or two ago, of about ten pounds weight, had a roe which weighed two pounds nine ounces, and the skin in which the eggs were enveloped (they were not in the loose state in which they are found just before exclusion) weighed three ounces, after all the eggs were washed from it; so that there were thirty-eight ounces of eggs. I weighed fifty of them, and found they weighed sixty-five grains. At that rate, thirty-eight ounces would give 12,788, and 300 lbs. 1,615,000; but as they would be much lighter when dried and potted than when taken from the belly of the fish, we may safely estimate that the 300 lbs. would contain 2,000,000, a prodigious number to pass through the hands of one tackle maker in a season.

From "Loudon's Magazine of Natural History."

I have frequently found, when catching Trout for this purpose, that the milt and roe were not ready for exclusion; when this was the case, I put them into a wire cage, which I sunk in the water, examining the fish every week, until I found they were in a fit state for the experiment.

I fancy that if the ova come in contact with the air on exclusion, they are not so readily impregnated as if they are always covered with the water, and therefore I have laid some stress on the desirableness of keeping the air excluded from the ova as much as possible.

There is, however, one fact which must lead a casual observer to suppose that the ova are impregnated twelve months before exclusion. It is this: the male Par (Salmon fry) are at this season, October, full of milt, almost ready for exclusion; whilst, in the female, the ova are so small that they require a microscope to see them individually, and the whole ovary is merely like a thread, leading to the conclusion that either the milt of the male is not required for the female Par, or the ova are impregnated twelve months before exclusion. The fact is, that the milt of the Par is used to impregnate the ova of the Salmon on the spawning beds.

When I commenced this paper I had no doubt that hybrids had been produced between the Sprod (sea Trout) and the common Trout; since then, having seen the fry said to be so produced, and on making some further inquiries, I find there is some doubt whether the female was a Sprod, or merely a white Trout, and therefore I cannot confidently assert (as some time ago I believed I could) that hybrid fish had already been produced. As some of my readers may not know what a Sprod is, it may be necessary to explain. In the Ribble we have a fish ascending from the sea in July and August, weighing from six to ten ounces, which, in appearance at least, is a miniature Salmon. I believe the same fish is called a Whitling in Scotland. Besides this, we have a similar but larger fish, which begins to come a little earlier, and which weighs from one to three pounds; this, in the Ribble, is called a Mort (in Scotland a sea Trout). Both these fish (if they are two species) afford splendid sport to the angler, who must never consider them beaten until he has them in the landing-net. They are also delicate eating.

Note on cross-breeding of Fish.

Since the above paper was published, the breeding of Hybrids has been successfully accomplished. I have had fish sent from two different gentlemen living on the banks of the reservoirs belonging to the Liverpool Waterworks; these were beautiful fish (three in number), more like the sea Trout than the Salmon, and the largest of them weighing two pounds. I had put them into the brooks running into the reservoirs three years before.

I also learn from a friend that a beautiful specimen of the ombre Chevalier (French Char) was taken out of the Rivington reservoir. About a thousand had been put there by me two years before.

Persons conversant with the habits of birds will readily comprehend me; for the sake of those who do not, I will just observe that the flight of all the Wagtails is very peculiar, being a succession of great leaps in the air (if I may be allowed the expression), which form a series of curves, the bird rising considerably at the commencement of each effort, and sinking again at the close.

The intrepid and unfortunate traveller Joseph Ritchie, who accompanied Captain Lyon's expedition to Fezzan, and died there in 1819. Mr. Ritchie was a native of Otley, and an intimate friend of Mr. Garnett and his brothers. The beautiful poem from which the quotation is taken is printed in Alaric Watts's "Poetical Album."

1853.--I regret that in 1853, and for some years previous, we have not seen one. I fear they are extinct. The smaller kind are still numerous.

The male Par is an exception to this rule.

It appears to be a beautiful provision of Nature that mixture with water should increase the sphere of its action. Spallanzani found by actual experiment that three grains of the seed of a male frog might be diluted with a pint of water without destroying its stimulating power. See "Dissertations," vol. ii. p. 142, chap. 3, Ed. "Mag. Nat. History."