PRACTICAL WORK. 329 



for dissection, and spare others that are harmless. It 

 is said that the authors of a well-known contribution 

 to the literature of original research in histology used 

 as their chief matel'ial the mice caught in their own 

 house. This example of careful economy of animal 

 life is one worthy to be recollected. 



Many of the invertebrate specimens required may be 

 selected on a similar principle to that already recom- 

 mended, i.e. avoiding needless destruction so far as 

 possible. The cockroach that infests the kitchen may 

 be easily induced to decree its own execution in the 

 fashion it prefers, like the famous Duke of Clarence, if 

 you set — not "a butt of malmsey wine," but a flat dish 

 filled with plebeian, beer; in this it may be trapped 

 by dozens. The snails that devastate your cabbages 

 may be picked out of the bucket in which the gardener 

 drowns them, and used for purposes of science ; and 

 the common cabbage caterpillar, and many other 

 garden pests may be got rid of in the same way. 

 Drowning, or the use of ether or chloroform, are the 

 most humane- ways of disposing of almost every animal. 

 In using either of the two latter, soak a sponge with 

 it, and place it with the animal under a jar or bell- 

 glass well fitted down. 



The student may either begin, as directed here, with 

 the larger animals, or begin with the smaller in- 

 vertebrate forms, and work onwards to the higher 

 types. The former plan has the advantage of begin- 

 ning with structures big enough to be seen without 

 difiiculty. The advantage of the latter is, that the sen- 



