PART II. 



INTBODUCTION. 



IN publishing methods of preparing, staining, hardening 

 and mounting microscopic objects, I have adopted the 

 system employed in my classes for some years past ; that is, 

 each separate stage of procedure is arranged in successive 

 lessons or chapters. Of course, a subject such as this can- 

 not be so lucidly described in writing as by demonstration, 

 but it has been my aim to make it as clear as possible, so 

 that if the instructions are carefully followed and practised 

 successful permanent work can be performed ; but it is only 

 by most scrupulous care and constant practice that any 

 degree of success in this work can be attained. 



LESSON 1. 



HARDENING ANIMAL TISSUES FOR MICRO- 

 SCOPICAL EXAMINATION. 



Fresh untreated tissues are usually unsuited for micro- 

 scopical purposes, but it is sometimes advisable to observe 

 the appearance of a fresh specimen. When this is desired 

 the tissue must be examined in a fluid that will alter its 

 character as little as possible. Normal or J per cent, salt 

 solution answers this purpose. Tease out a small piece of 

 the tissue on a slide in some salt solution, apply a cover- 



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