1894.] MICROSCOPICAL JOURNAL. 123 



thorough microscopical training entirely adapted to the wants 

 of medical students." We are glad to announce that, notwith- 

 standing the considerable size of the book and its many illus- 

 trations that it is placed upon the market at a price within tlie 

 reach of all. 



The Earthworms. — Those interested in the study of Oli- 

 gochaHs will find in the Memoirs of the California Ac^adeniy 

 Science, II, No. 3, just issued, the descriptions of several new 

 species and a series of 12 large plates which contain most inter- 

 esting anatomical figures. The paper constitutes a monograi)h 

 on the family Eudrilida?. 



MICROSCOPICAL APPARATUS. 



Section cut Versus Natural Preparations. — Staining and 

 section cutting is one of the most valuable methods in use in 

 microscopical investigation, but it should be avoided in many 

 instances where the object can be examined in a satisfactory 

 manner without undergoing this process. 



The hardening process in alcohol of necessity contracts the 

 soft tissues, while the knife divides some objects in a manner to 

 render them hardly recognizable, in fact, in such cases the speci- 

 men is transformed from its true and natural aspect, to some- 

 thing false and unnatural, and it is a question, if due allowance 

 is always given, in the examination of hardened section prepara- 

 tions to these facts. 



This is very apparent in two mounted preparations now be- 

 fore me, one a preparation of Trichina? in the muscle of the hog, 

 hardened, stained and cut in sections ; the second is the same* 

 object, simply pressed, dried and mounted, as I will presently 

 describe. 



A glance is sufficient to detect, in this case the value of the 

 second method over the first. The former shows the trichinge 

 much decreased in size, of an unnatural color, and their forms 

 mangled and distorted, while in the latter case they have all 

 the appearance of nature, as seen in a fresh preparation — the 

 animals and the cysts are perfect and lie in their usual place. 



The latter preparations are made by taking very fine particles 

 of the fresh muscle, using for the purpose a sharp pair of scissors, 

 and placing then] between two pieces of thick glass, and pressed 



