222 JOHN SUNDWALL 



(to which the sections adhered) were then placed in alcohol and 

 ether until the celloidin was dissolved (15 to 20 minutes) ; trans- 

 ferred to absolute alcohol, 95 per cent alcohol, 70 per cent alco- 

 hol, and finally to water; and digested in pancreatin, which 

 required from one to three days. 



Tissues fixed in any of the chrome salts were not affected by 

 pancreatin in one week's time. 



4. For further study of the connective tissue, tissues were 

 fixed in Zenker's solution, embedded in celloidin and stained as 

 follows: (a) for coUagenic fibres and smooth muscle — Van 

 Gieson's, Mallory's and haematoxyUn and eosin; (b) for elastic 

 fibres — Weigert's and Unna-Taenzer ('10). 



5. For the study of fat in connective tissue, pieces of gland 

 were fixed in 10 per cent formalin twenty-four hours, washed, 

 cut by frozen method, and stained by Herxheimer's ('10) method 

 — absolute alcohol 70 cc, sodium hydroxide (10 per cent solution) 

 20 cc, water 10 cc, Sharlach R. to saturation. After staining 

 for from five to ten minutes sections were washed in 70 per cent 

 alcohol, washed in water, and mounted in glycerin. 



IV. For the study of secretion granules and the finer histologi- 

 cal characteristics of the cell. 



1. Granules in the intercalary ducts — Fixed in Zenker's, 

 embedded in celloidin, fastened to slides (see III, 3); celloidin 

 dissolved off; and section stained in muchaematein or mucicarmin 

 prepared according to Bensley's method (see Stains). 



2. Granules in the tubules as well as those in the intercalary 

 ducts and the minute cell structures — Small pieces of tissues 

 were fixed in the following solutions, embedded in paraffin, and 

 cut from 2 to 5 yu thick. 



(a) Bensley's ('96) sublimate alcohol bichromate solution — 

 equal parts of saturated solution HgCU in 95 per cent alcohol and 

 2^ per cent aqueous solution of KoCroOy. Small pieces of the 

 tissue were placed in this fixative for about three hours. The 

 solutions were not mixed until time of using. Fresh mixtures 

 were used every thirty minutes during fixation. 



(b) Modification of Kopsch's formalin bichromate solution — 



