Preston Kyes 39 



work. Pancreatin digestion was used as suggested by Mall and Spalte- 

 holz. According to Mall's method, sections of fresh tissue are digested 

 in the following solution : 



Pancreatin, 5 gms.; bicarbonate of soda, 10 gms.; water, 100 ccm. 

 The resulting specimen is washed by shaking in a volume of water and 

 then allowed to dry on the slide. To stain the section, a few drops of 

 the following solution are allowed to dry on the specimen: 



Picric acid, 10 gms.; absolute alcohol, 33 ccm.; water, 300 ccm. 

 The specimen is then immersed for one-half an hour in the following 

 solution : 



Acid fuchsin, 10 gms.; absolute alcohol, 33 ccm.; water, 66 ccm. 

 Upon removal, the tissue is washed with the picric acid solution, de- 

 hydrated, cleared in xylol and mounted in balsam. 



The method of digestion suggested by Spalteholz has been of especial 

 service because of the support given to the delicate framework by the 

 glass slide and because of the accuracy of the control. According to 

 this method the tissue to be digested is fixed in a one per cent solution 

 of mercuric chlorid in thirty-three per cent alcohol for twenty-four 

 hours. Each succeeding twenty-four hours the tissue is transferred 

 to fresh alcohol increased ten per cent in strength, until absolute 

 alcohol is reached. The tissue is imbedded in paraffin and cut in 

 serial sections from 6f to 20 microns thick. The sections to be digested 

 are fixed to the slide by the water method and the process continued 

 as follows: 



Eemove the paraffin with xylol; wash in absolute alcohol; 

 immerse in benzine at 38° C. for 24-36 hours; wash in ab- 

 solute alcohol followed by 95 per cent alcohol; wash in water 

 five minutes; digest in a solution of pancreatin at 38° C. for 

 12-48 hours; wash in water 10 minutes; stain with iron hse- 

 matoxyliu; mount in balsam. 

 By substituting acetic alcohol ' for the graded alcohols, the time 

 required for fixing may be reduced from several days to a few hours. 

 The pancreatin solution was employed as follows: 



Pancreatin ferment (Griibler), 1 part; sodium bicarbonate, 



20 parts; thymol, 10 parts; distilled water, 10,000 parts. 



I^he digestion of hardened tissue in bulk was employed as follows: 



Small pieces of tissue were hardened 4-12 hours in acetic alcohol and 



dehydrated in absolute alcohol. They Avere then extracted with ether 



for 10-14 days. The tissue was then digested in an aqueous solution 



sCarnoy: La Cellule, T. Ill, 1886. 



