300 AQUATIC MICROSCOPY FOR BEGINNERS. 



animal down to the insects, forms an important class 

 of objects for study. Every animal has characteristic 

 hair that may be recognized if the observer have suf- 

 ficient skill in the use of the microscope and suf- 

 ficient knowledge -of the subject; but to attempt to 

 identify hair demands careful work with high powers. 

 It cannot be done with a pocket-lens, nor with a one- 

 inch objective, unless the specimen is exceedingly 

 common, and the observer has examined it often and at- 

 tentively. The difficulty is increased by the fact that 

 the hair of our small mammals differs greatly in micro- 

 scopic structure in different parts of the body. I once 

 heard a lecturer claim to have identified an unknown 

 sample of hair with a Coddington lens, a claim that he 

 would have hesitated to make if he had known any- 

 thing about the subject. A single fibre of hair may be 

 recognized as such, and can be very readily distin- 

 guished from a fibre of wool, silk, or cotton, all Of 

 which the beginner should examine, since they will 

 often be found on the slide and may be mistaken for 

 something entirely different. Hair is easily accessible 

 from the cat, mouse, horse, and other animals. It 

 should be examined in water with a high power. The 

 hair of the mouse is peculiar, as is also that of most 

 bats. Colored fibres of wool are often seen on a slide, 

 having dropped there from the observer's clothing or 

 been loosened from the carpet. These must not be 

 mistaken for a remarkable class of worms. 



II. Hairs of Anthrenus Larva. — The "buffalo 

 beetle" (Anthrenus scropkuldrice, and its relative, A. 

 musedrum) are pests that are becoming much too com- 

 mon in our houses. The larvae, however, may be 

 utilized by the microscopist as a supply for hairs of 



