Country Walks of a Naturalist with His Children

by W. Houghton

And now you say the cuckoos leave before the end of July. I think you must have made a mistake somehow." I am glad that you have found out the error, if it is one. Old rhymes are not always to be trusted; but I suspect that the couplet "Come August, go he must," means to imply that the cuckoo does never really stay so late with us. I must not, however, forget to tell you that it is the old parent birds that leave us early; young birds remain till September, and even October, but they have not by that time acquired the cuckoo note. If you ask why cannot the old cuckoos stay with us a little longer, and then all go away together as a family party, young and old, in September, instead of being in such a hurry, I have only to say that it is the fashion amongst cuckoos, and of course cuckoos, like certain other animals, must be in the fashion. This is Dr. Jenner's explanation of the peculiar habits of the cuckoo in respect of its eggs. I am not prepared to say whether or not it is sufficient to explain them. The cuckoo's egg is very small when compared with the size of the bird; it is of a pale grey tinged with red.

"But how does the cuckoo's egg get into some of the nests?" asked Willy; "for some of the nests in which the cuckoo's egg is found are too small to allow the cuckoo herself to enter to lay her egg." You are quite right; I believe it has been proved that the cuckoo lays her egg on the ground, and carries it in her bill into other birds' nests.

HORSE-TAIL.

"Oh! papa," said Jack, "what is this curious plant that grows so abundantly on the grass here? I know it well by sight, but do not know its name." It is a spike of horse-tail; see how the stem is marked with lines, and how curiously jointed it is, and quite hollow except where the joints occur. The fruit is borne at the top of the plant (a); see, as I shake it, what a quantity of dust comes from it; this dust is the fruit, or spores as they are called; each spore is of an oval form, with four elastic threads. If I were to put some of this dust on a glass slide, and look at it under the microscope, I should see a curious sight. The four threads would be spread out, but if I were to breathe on the glass, these threads would coil themselves round the oval body; but as soon as the effect of the moisture had passed away, the threads would shoot out again in the same position as they were at first, causing the spore to leap as if it were alive. The stems are of two kinds, fertile and unfertile; the one you have in your hands is a fertile spike, and appears only in the spring; the unfertile ones have no dust-like fruit, and have numerous jointed branches growing in rows, or whorls as they are termed, round them; they remain throughout the summer, and in some places form quite a thick cover. Feel how rough the stem is; this is due to the presence of a quantity of silex or flint in it; on this account some of the species are used for polishing purposes. One kind, under the name of "Dutch rushes," is imported from Holland, being used for polishing mahogany, ivory, metal, &c. The horse-tails for the most part grow in moist ground, in ditches and on the borders of lakes; some, however, are common in corn fields and on the roadside. In this country they do not attain a height of more than a few feet, but in tropical countries one or two species grow to the height of sixteen feet or more.

HYDRÆ, ON ROOTS OF DUCKWEED.

Now for a dip with the bottle in this pond. I will try and catch a few Hydræ. Strange animals, indeed, they are, and strange is their history; but let us catch a few first. Nothing yet in my bottle like a hydra. Ah! now we have one or two. You see a small creature sticking to the stem of a bit of duckweed; around its mouth are five or six little projections. At present they are contracted; but the hydra is able to lengthen them out, when they appear as long, thin lines, which are used as the creature's fishing-lines; it is not much larger than a pin's head at present, but it can stretch its body out as it does its lines. I will take a handful of duckweed, and put it, dripping wet, into this bag, and when we get home we will place the whole in a glass vessel full of water. In the course of half an hour or so, we shall, no doubt, see several hydræ, probably of different species, in various attitudes—some hanging loosely down, others erecting themselves in graceful curves and throwing out their arms or tentacles many times longer than their bodies; others shooting up their arms right above their heads; others contracted, looking like miniature dabs of jelly; others attached head and tail to the side of the glass; others floating on the surface of the water, their tail-ends sticking out and serving to keep them from sinking; some of a beautiful grass-green colour, others light brown or flesh colour, others almost white, others red. These creatures may be cut into several parts, yet each part will grow again into a perfect animal; young ones bud out of the sides of the parents. Some have said that they can be turned inside out, and find no inconvenience whatever from the operation. "But how," asked Willy, "could anybody manage to turn so small a thing as a hydra inside out?" It does seem an impossible task, I confess, and a man must have much skill and patience to enable him to accomplish it. However, I will give you the description of an attempt made many years ago by a celebrated naturalist of Geneva, named Trembley, who made the hydræ or fresh-water polypes a study for many years. This is what Trembley says:—"I begin by giving a worm to the polype on which I wish to make an experiment, and when it is swallowed I begin operations. It is well not to wait till the worm is much digested. I put the polype, whose stomach is well filled, in a little water in the hollow of my left hand; I then press it with a small forceps nearer to the tail end than to the head. In this way I push the swallowed worm against the mouth of the polype, which is thus forced to open, and by again slightly pressing the polype with my forceps I cause the worm partly to come out from its mouth, and thus draw out with it an equal part of the end of its stomach. The worm, coming out of the mouth of the polype, forces it to enlarge itself considerably, especially if it comes out doubled up. When the polype is in this state, I take it gently out of the water, without disturbing anything, and place it on the edge of my hand, which is simply moistened, so that it may not adhere too closely. I oblige it to contract more and more, and this also enlarges the stomach and mouth. The worm then is partly coming out of the mouth, and, keeping it open, I then take in my right hand a hog's bristle, rather thick and without a point, and I hold it as one holds a lancet for bleeding. I bring its thickest end to the hind end of the polype and push it, making it enter into its stomach, which is the more easily done as in that part it is empty and much enlarged. I push on the end of the hog's bristle, which continues to invest the polype. When it reaches the worm, which holds the mouth open, it either pushes the worm or passes by its side, and at last comes out by the mouth, the polype being thus completely turned inside out."

HYDRA, WITH YOUNG ONES BUDDING OUT FROM ITS SIDE.