38 



THE AMEEICAN MONTHLY 



[February, 



scope with triple nose-piece and three 

 or more lenses, of powers as follows : 

 xY^" or x", yi"ox Y", %"oY y'; 2" 

 and i" Huyghenian eye-pieces, and 

 Y" or %" solid ocular, all of which 

 should drop easily into their places. 

 This is a point that microscOpists 

 should insist upon — then, and only 

 then, will the makers learn wisdom. 

 The microscope should have a rack 

 motion, and the fine adjustment 

 should be behind, if for no other 

 reason than convenience ; the stage 

 not more than %" thick, including 

 carrier or mechannical stage, and cer- 

 tainly not less, as it cannot thus be 

 made, and at the same time be steady. 

 It must have a stop for the Maltwood 

 finder. The mirror should swing 

 above the stage, the diaphragm of the 

 iris pattern, or so constructed as to 

 work close to the slide. The swing- 

 ing substage I would not insist upon, 

 though at times it may be a conveni- 

 ence, it is not a sine qud non as some 

 would have us believe. 



In addition, a camera lucida that 

 can be used in all positions of the 

 microscope is a necessity. Don't 

 forget a polariscope in the outfit. This 

 is indispensable ; hence a stand 

 having a shifting, polarizing appara- 

 tus, as the " lithological " stands, 

 would, in some respects, be the best 

 stand for our work. A bull's-eye con- 

 denser, eye-piece and stage microme- 

 ters, section cutters, knife and car- 

 riers, a lamp with an Argand burner 

 are all necessary articles. 



For dissection and tearing, a dis- 

 secting microscope, scissors, needles, 

 knives, brushes, etc., must be provid- 

 ed each student, as well as turn-table, 

 nest of porcelain saucers (not less 

 than eight in a nest), mounting media, 

 finishing cements, staining fluids, al- 

 cohol, etc., and capped bottles to con- 

 tain them, these with small spirit- 

 lamp, bell and watch-glasses, will com- 

 plete an outfit. 



A set of reagents for urinary analy- 

 sis, acids, test-tubes, beakers, wash- 

 bottles, water and sand-baths, large 

 spirit lamp, drying oven, Bunsen bur- 



ner, imbedding material, etc., should 

 occupy the centre of the room on the 

 chemical table. 



A cabinet supplied with normal 

 and pathological slides is a great 

 help to students, as well as all the 

 important current and standard litera- 

 ture bearing on the subject. 



The course of instruction should 

 begin with a thorough elucidation of 

 the mechanical and optical principles 

 involved in the manufacture of the 

 microscope. I clip the following from 

 the Journal of the Royal Microscopical 

 Society for December, as bearing di- 

 rectly on this point : " Microscopists 

 have for many years insisted that it is 

 absolutely essential that histologists 

 should be grounded in the theoretical 

 principles applicable to the instru- 

 ment with which they work, and that 

 if this is not done, not only will er- 

 roneous interpretations of structure 

 be put forward, but many points of 

 importance will be altogether missed. 



" In England (and America, too) 

 this view has not been accepted in 

 practice ; and an histologist who at- 

 tempted to determine the true struc- 

 ture of an object by experimental or 

 theoretical optical considerations was 

 a rarissima avis, indeed." 



It would be well to acquaint the 

 student next with the manipulation 

 of his lenses, and the ascertaining 

 of their powers. Follow this with in- 

 struction (practical of course) on the 

 use of immersion or collar-adjustment 

 lenses and eye-piecing. 



A thorough study of the normal 

 fluids of the body and the simple tis- 

 sues should immediately be followed 

 by the study of the same in diseased 

 conditions. This method I prefer to 

 that of postponing pathological his- 

 tology until the entire course of nor- 

 mal histology has been gone over. 

 The student thus sa^^es much time 

 and learns more rapidly the distinc- 

 tive differences in the appearance of 

 the tissues, after the simple tissues 

 the membranes and organs are each 

 considered in the way above stated. 

 I hope this paper will excite com- 



