2 KANSAS UNIVERSITY QUARTERLY. 



Another means used was to soften the specimens in warm water 

 then transfer to fifty per cent alcohol, then to ninety-five per cent 

 alcohol, from here through the clearing mixture into balsam. This 

 I found better, in that it insured the retention of the plates present 

 but it had the objection of not rendering old and heavily chitinized 

 scales transparent. 



For a new bleaching agent, chloral hydrate, saturated solution, 

 boiling specimens in this under cover for a few inoments and also 

 by leaving in the fiuid under cover for twelve to twenty-four hours. 

 The latter method — leaving in for a da)' or less — gave the best re- 

 sults, rendered the specimens transparent and kept them reason- 

 ably firm. It did not appear to affect the plates and spines; did 

 not leave any undesirable substances upon the specimens. From 

 the chloral hydrate they were taken into the water and then through 

 the process previously described. 



In experimenting with the action of xjdol upon the plates it was 

 found that it rendered them very brittle and left them undesirably 

 transparent, so that in some specimens mounted in x3dol-balsam I 

 noticed a tendency to render the plates of the same refractive index 

 as the balsam. Glycerine as a mounting medium was tried, and 

 it was found that specimens could be more readily taken from a 

 chloral solution into glycerine than by any other method used. 

 The objection to the glycerine is, of course, that permanent mounts 

 require to be incased in cement. Gl3cerine jelly, I think, will 

 largely overcome this difficulty, and I expect to test it in my sub- 

 sequent work. 



Having the mounts ready for study I found daylight not always 

 the most satisfactory light for revealing the points desired, so that 

 the light of the Welsbach burner passed through a liter balloon 

 flask, filled with a solution of copper sulphate, rendered the de- 

 sired clearness by the addition of ammonia (NH.^), the test being 

 a white light thrown upon the reflector. This illuminatmg apparatus 

 is spoken of in Botanischcs Practicum, Strasburger, iHgy, and Micro- 

 scope and Microscopical Accessories, Zeiss, No. 30, i^!g5. Mr. Mc- 

 Clung, of the department of Zoology, in his work tried the ad- 

 dition of a drop or two of saturated alcoholic solution of saffron to 

 the fluid in the flask. This I consider advantageous; enough be- 

 ing added to give the light a tinge of pink, which gives good con- 

 trasts with the yellow subject. I had endeavored to find a stain 

 that would hold in firmly chitinized specimens, but met with little 

 success. This pink . light, showing the necessary contrast, as it 

 does, served the same purpose at a great saving of time and labor. 



