108 SUMMABY OF CUREENT RESEARCHES RELATING TO 



of Wigand's peculiar theory of fermentation, and the third of the 

 anamorphosis of protoplasm. 



Yeast-poisons.* — Herr H. Schulz has experimented on the effects on 

 ferments of very dilute solutions of well-known yeast-poisons, such as 

 corrosive sublimate, iodine, potassium iodide, bromine, arsenious acid, 

 chromic acid, sodium salicylate, and formic acid, and finds that in all 

 cases it promotes the activity of the fermentation. The mode of experi- 

 ment was as follows. In each of .a number of glass cylinders of 200 ccm. 

 capacity were placed 50 ccm. of a 10 per cent, solution of grape-sugar, 

 and to each was added 1 ccm. of fresh baker's yeast and distilled water. 

 The cylinders were closed by a metal lid, which was screwed in, and in 

 this were placed a long divided glass tube and a short one, furnished 

 with a cock for ventilation. The lower end of a long tube dips into a 

 vessel filled with mercury, the upper edge of which projects above the 

 level of the nutrient solution in the cylinder. The carbon dioxide pro- 

 duced during fermentation presses up the mercury in the divided tube, 

 and the course of the process of fermentation was concluded from that 

 of the column of mercury. All the cylinders were placed in a water- 

 bath heated to 21° C, and were submerged, so that any defect in the 

 closing of the cylinder would be shown by the ascent of bubbles of gas. 



* Arch. f. d. Gesammt. Physiol. (Pfluger), xlii. (1888). See Bot. Ztg., xlvi. 

 (1888) p. 610. 



* I t^aH- 



