1162 



Journal of Applied Microscopy 



1. Linear adjustment of substage condenser, crater, and center of camera- 

 back to obtain their coincidence with the optical axis of the microscope. 



2. Focus of source of illumination upon object by means of substage 

 condenser. 



3. Focus of objective upon object. 





% A 



m\ m 



■ V 





-^A* ^ ^4 



Figure 4. — Metaphase of the first spermatocyte. The chromosomes of the same cell do not divide 



simultaneously, as may be seen at " a ". Sometimes they form rings as seen at " b ". 



In the cell marked " c " the archoplasmic fibers are sharply in 



focus. Same object. 1000 diameters. 



4. Final simultaneous projection of crater and object images upon ground 

 glass of camera. 



5. Diffusion of light by ground glass between source of illumination and object. 



6. Adjustment of substage iris diaphragm. 



7. Exposure of plate. C. E. McClung. 

 University of Kansas. 



An Improvised Microtome. 



On a recent visit to the College of Physicians and Surgeons in Boston, the 

 writer saw, among other ingenious contrivances, a microtome devised by Dr. 

 Shurtleff, of the above named institution, and made by him at a cost of fifty 

 cents, for cutting the micrometer screw. Since my visit I have myself made 

 a similar microtome at the small cost of two hours' work, since a common screw 

 was employed instead of a micrometer. Thinking that possibly the idea may be 

 of use to some other investigator, I will venture to offer the following description : 



The first essential is, of course, a knife; and, while a regular section razor is 

 preferable, an ordinary razor will answer. In the absence of either, however, I 



