466 ZOOLOGY. 



Amoeba, Paramecium and Hydra may be obtained by post 

 from Mr. Bolton. The two latter can easily be studied 

 under the microscope (Hydra with the naked eye also), but 

 we do not advise any beginner to attempt to find amoeba for 

 himself the mud in which it lives is always full of an 

 abundance of other strange creatures, much more conspicu- 

 ous than the one he is in search of. 



Earthworms can be dug up in any garden or field. They 

 are killed by immersion in methylated spirit. Mussels 

 occur in most English rivers, and crayfish in many : these 

 types can also be had through the post from dealers. They 

 are killed by immersion for a minute or so in water as hot 

 as the hand can just bear. 



For preserving animals that cannot be completely dis- 

 sected on one day, common methylated spirit answers very 

 well. It both preserves and hardens, but has no great pene- 

 trating power, so that if large animals are placed in it care 

 should be taken to open them up as much as possible to let 

 the spirit have access to all parts. Formalin has lately come 

 into very general use as a preservative; it has several 

 advantages over spirit, particularly its penetrating power, 

 but its vapour is very irritating to the nose and eyes. 

 Formalin is really a standard solution of formic aldehyde in 

 water. For preserving animals or parts of them, it may be 

 very considerably diluted (4 to 6 parts of formalin to 100 

 of water). In its full strength it acts as an excellent 

 hardening re-agent for animals of which sections are to be 

 cut e.g. the mussel (removed from shell), brain and spinal 

 cord of rabbit or dogfish, rabbit-embryos and the earthworm. 



SUGGESTED ORDER OF PRACTICAL WORK. 



By the time the student has read the first three chapters, 

 he may begin dissecting the rabbit ; but if he is quite with- 

 out both help and experience, he would do better to wait 

 until he begins chapter vii. (The Skeleton), when he can 

 take a dead rabbit (as sold for food) and boil it whole until 

 he finds that the muscles (flesh) can be removed quite 

 easily from the bones. He can then proceed to clean the 

 skeleton completely, taking care to keep all the bones in 



