362 KANSAS UNIVERSITY SCIENCE BULLETIN. 



I found that 2 per cent, formic acid would produce the same 

 results, if left on the tissue no longer than five minutes. After 

 having the tissues thus so well removed from the objectionable 

 chitin, they were placed in the several fixatives. It was found, 

 however, that the acetic acid shrank the cells — especially the 

 so-called "ganglion-cells" — and the formic acid did not work 

 well with some of the fixatives, 



I next found that the fixatives could be put upon the tissue 

 at once with the same results as the acids used, I cannot say 

 that this is true for all fixatives, but I am inclined to think that 

 it is, since its results were satisfactory for those tried, espe- 

 cially with the chrome-oxalic mixture, the method which I 

 found among the best for this work. 



There is one precaution, however, to be observed. The tis- 

 sue should be removed from the chitin in from three to five 

 minutes after being killed with the fixative, A longer time 

 seems to make the tissue soft and thus impossible of removal 

 without tearing. If left for months in a preservative such as 

 10 per cent, formalin it gets crumbly or brittle and the results 

 are not satisfactory, 



A great many different fixatives and stains were employed, 

 most of which were after the direction of Hardesty,^^ Houser,^- 

 and Lee,^^ with some few individual variations. Over seventy 

 diff'erent preparations were mounted. 



Flemmings' fluid, so helpful for cytological purposes, proved 

 to be of no value on the heart-tissue. 



Unsatisfactory results were also obtained with picric acid, 

 in which specimens were fixed for two or three days and then 

 washed in alcohol; Gilson's fixed from one to two days; Per- 

 eny's fluid for eighteen hours; chrome-silver, as described by 

 Houser; gold chlorid, according to Hardesty (p, 51), and mer- 

 curic chlorid and formalin (10 per cent.) ; silver nitrate, also 

 described by Hardesty (p, 41) ; and even Bethes' injection 

 method, by Hardesty (p. 43). In the latter case the sections 

 were not well fixed and would not clear up, although the 

 method was carefully tested. Houser reports a similar result 

 with Bethes' method. 



Most satisfactory results were obtained with 10 per cent, 

 formalin as a fixative, and iron-hsematoxylin as a stain; and 



11. Hardesty, Neurological Technique. 



12. Houser, G. L., Jour, of Comp. Neurology, vol. XI, No. 2, 1901. 



13. Lee's Vade Mecum, fifth edition. 



