174 INTRODUCTION TO ZOOLOGY. 



market, it will be found better to purchase them fresh 

 when they are needed. 



For the proper preservation of vertebrate material 

 while it is being studied, two plans may be used. 

 Usually it will be found advantageous to study verte- 

 brates in the winter, that being the most convenient 

 time for procuring and preserving the material. 

 A large ice box will be found very convenient to 

 keep the specimens in from day to day. If the 

 weather is warm, the ice box may have ice to keep 

 the specimens cool. If the weather is very cold, 

 the ice box may serve to keep the specimens from 

 being frozen too hard, while still cold enough to be 

 preserved. 



A more satisfactory way, however, is to preserve 

 the vertebrate specimens in one per cent formalin. 

 Each day at the close of the study period the speci- 

 mens are put into a large receptacle, like a wash 

 boiler, galvanized iron bucket, or any other article 

 of that nature. The next day they must be taken out 

 and distributed, work being resumed where it had 

 been left off. 



Specimens preserved in this way will need to be 

 tagged. Small strips of zinc written on with a lead 

 pencil and tied to the specimen Avith a string have 

 proved very satisfactory. 



Tlie principal objection to such use of formalin is 

 that it bleaches out the blood vessels, making them 

 difficult to trace ; but it rather improves the muscles 

 and nervous system. 



For the satisfactory handling of vertebrate mate- 

 rial, some large iron pans like baking bans (which 

 can be procured very cheap) will be found convenient. 



Earthworms should be procured fresh if possible ; 

 but they may be preserved in formalin. 



Clams and oysters can be bought in the market ; 

 but if available markets are not near, fresh-water 



