Within the Volvox sphere we may observe a number, usually one to eight, of smaller spheres. These are so-called daughter colonies which have arisen from the continued division of special cells. They develop, fairly rapidly, into young Volvox colonies, then they burst through the cells of the parent colony, swim out into the water and quickly grow to the size of the Volvox from which they were formed.
There is another kind of Volvox of a yellowish colour and much smaller than Globator, the big one is the one we must procure; it is much more easily studied.
Certain of the plants we shall find in our pond are so animal-like in their movements, that the microscopist who sees them for the first time may wonder whether we are not mistaken in calling them plants. We have already described the common Chlamydomonas, with its curious jerky method of propelling itself through the water. There is, however, an equally common one-celled, pond-frequenting plant which has puzzled naturalists even more, for it certainly possesses many very animal-like characteristics. Its name is Euglena Viridis and we require our highest magnification to examine it for it does not exceed one-two hundred and fiftieth part of an inch in length. Usually, Euglena is cigar-shaped but, as it possesses the very unplant-like characteristic of not having a firm cell wall it can change its shape to a considerable extent and it often assumes curious forms. At the forward end of this minute plant there is a single whip-like thread, by means of which it swims; a little below the base of the whip, there is a red eye spot. Elsewhere we have described how the protean animalcule feeds by flowing round its food-material, Euglena feeds in a similar manner, but it also feeds after the manner of a plant. When this active little plant is about to increase it either divides into two lengthways or becomes surrounded with a firm wall within which it breaks up into a number of young forms which are released later by the bursting of the wall.
Photos by Flatters & Garnett
1. Bladderwort
A British water plant which entraps small animals in its bladders and digests its captives.
2. Spores of Horse Tail
These spores with their thread-like outgrowths vary in appearance according to the moisture in the air.
3. Hairs on a Potato Leaf