PECULIARITIES OF DAPHNIA AND ITS ALLIES. 



397 



vessel, while the other half rests on their upper edges. Through 

 this piece of cork a fairly long and stout pin is driven and 

 worked about until it moves without requiring much effort. 

 The point of the pin is next filed down until it is a thin wire 

 of not much more than about yi^ " in diameter, and the tip 

 is then bent round, at right angles to the main shaft, into a 

 tiny loop which is intended to retain the drop of cementing 

 material. It is necessary to have a loop,* as the cement will 

 be found to retreat up the pin if a sharp point only be used. 



Presuming that the glass trough filled with water is in readi- 

 ness, and that the cement is close at hand, the next thing to 



be done is to place the animal to be examined on a glass slip, 

 and, with a piece of blotting paper, to remove as much as possible 

 of the moisture clinging to it. Without loss of time the loop 

 at the end of the pin must now be dipped into the cement and 

 gently applied to the head or other part of the animal, according 

 to the particular investigation one has in view. In a few 

 seconds the cement, if suitable for the purpose, will have 

 sufficiently hardened to allow of the animal, suspended from the 

 end of the pin, being placed in the water in the trough, and 

 its position adjusted for examination. If the various processes 



* A truncated tip will do in some cases, but it does not seem so 

 satisfactory as the minute loop. 



