50 NOTES ON 
They are very fond of sunshine, and on a 
cloudy day are seldom to be taken, as they 
descend to the bottom of the water and conceal 
themselves in the mud, or among the roots of 
aquatic plants. After a few days of fine hot 
weather, the pools in which they reside being 
partially evaporated, they become so numerous 
as to colour the water. They now attain their 
full size, and the richness and intensity of their 
colouring are at their maximum; the latter, 
however, they lose in a few days, if confined 
in a small vessel. Some specimens which I 
measured in this state, taken about the middle 
of June, were full one-thirtieth of an inch in 
length, while the largest bred in artificial infu- 
sions seldom exceed half that size. They were 
very numerous; a single drop of the water 
taken up on the head of our feeding-pin (see 
“‘ Microscopic Cabinet”) contained about thirty 
animalcules. They may be preserved alive for 
a considerable time, if occasionally supplied 
with a little hay. Some of those from which 
the drawings about to be described were taken, 
have been kept five years in a glass vase; their 
descendants, however, are much smaller, and 
have become perfectly colourless and pellucid. 
The minuteness of these creatures renders it 
