"What is this, papa," said Jack, "that I have found sticking to the roots of this water-weed; they look like the eggs of some creature?" They are not eggs, but the cocoons of a very common but pretty beetle called _Donacia_. See, I will slit one open with my penknife. There is the little animal inside, a white, fat, maggoty thing; it has two curious hooks at the end of the tail, it has only just framed its cell, and is about to change from the larval to the pupal state. Here you see are other maggots among the roots; they have not yet made a cocoon. I will open some more; here is one in its pupal condition. Here is another almost ready to come out as a beetle. The _Donacia_ have all a metallic appearance and very beautiful they are, whether blue, red, copper, or purple; the under side is covered with a fine silky down. They are found in great numbers on water-weeds, and being very sluggish are readily caught or picked off the plants they frequent with the hand. Do you notice those small, flat, brown or black dabs so common on almost any water-weed you pluck up? These are planarian worms, and though not of prepossessing appearance generally, are extremely interesting animals to study. These large, reddish, oval or round cocoons are the eggs of the planariae. Here is one of the largest of the family. It is of a milk-white colour, beautifully marked with delicate tree-like branches; sometimes this species (_Planaria lactea_) is of a light pink colour. The mouth is not situated where mouths usually are, in the fore part of the body, but almost in the centre. See, I will place this white planaria on my hand; do you notice that it protrudes something you might perhaps say was its tongue? It is not its tongue, however; it is a tubular proboscis, and is very strong and muscular, and unlike the soft body of the animal. By means of this proboscis the creature is enabled to pierce the bodies of other creatures and to suck out their juices. I have kept planariae under observation, and seen them drive this proboscis through each other. These black and brown dabs often feed upon the milky planariae. They are something like the hydrae in their power of producing lost portions of their bodies. Cut them in two or more pieces, each piece will grow into a perfect planaria again. These you see do not swim but crawl, or glide over the surface of plants in the water. Some kinds, however, different from these, are able to swim well. We have had a long and successful hunt to-day. Let us go. WALK VII. JUNE.