372 KANSAS UNIVERSITY SCIENCE BULLETIN. 



which facilitates sectioning, providing the material is not 

 allowed to be imbedded too long. 



Hot alcohol and hot Gilson's both give very good results 

 for larval forms, as has been noted by Headlee, '06, in his 

 work on Simulitim blood gills. 



Specimens killed in hot Perenyi's fluid, cut and removed to 

 fresh fluid for six hours and then transferred to 70 per cent 

 alcohol, were well fixed. 



But the best fixation that I have tried was obtained by the 

 use of Kable's Fixation. This was recommended to me by 

 Dr. Brues, of Harvard, who used it as a fixation for the Sto- 

 moxys calcitrans. It is made up as follows : 30 parts water, 

 15 parts normal 95 per cent alcohol, 6 parts formaline (40 

 per cent), 1 part of glacial acetic acid. The flies are killed 

 in this hot solution and transferred when cold to 70 per cent 

 alcohol. 



Since the Gilson's mixture mentioned above gave very satis- 

 factory results it might also be well to give directions for 

 making it. To make up a two-liter bottleful use: 

 30 cc. of 80 per cent nitric acid. 



8 cc. of glacial acetic acid. 

 40 grs. corrosive sublimate. 

 200 cc. of 60 per cent alcohol. 

 1760 cc. of distilled water. 



Infiltrating and Imbedding. When the specimens were 

 desired for study, they were graded up from the 85 per cent 

 alcohol to absolute alcohol in small glass dishes covered with 

 ground glass covers. If they were stored in 85 per cent alcohol 

 they were slipped up to 95 per cent and left for 48 hours to 

 harden. Then from this they were transferred to absolute and 

 left for a like time. From this they were transferred to a 

 vial which had been half filled with xylol and then filled with 

 absolute alcohol. Here they were left for 24 hours, after which 

 they were returned to a glass dish of pure xylol. The dish was 

 then placed on the top shelf of an electric drying oven, and a 

 few flakes of paraffin dropped into it. When dissolved more 

 were added and the dish placed nearer the heat. Bits of par- 

 affin were added from time to time for the following six hours. 

 By the end of that time the flies could be transferred to pure 

 melted paraffin and left there for 24 hours or longer. 



