300 



Mr. S. G. Paine. 



[July 12, 



the cell, making it impossible to obtain the usual white friable press cake, 

 but rather a brown-coloured and putty-like mass. 



This change may possibly take the form of a contraction of the cytoplasm 

 of the cell, and, since the depth of the layer of cytoplasm varies under 

 different conditions of the yeast, the amount of plasmolysis sustained by a 

 given sample of yeast when immersed in 20 per cent, alcohol may possibly 

 be determined by the relative proportions of the cell occupied by the 

 cytoplasm and by the vacuole. 



In Experiments 131-134 a gradual diffusion of solid matter from the 

 yeast into the surrounding liquid is observed to have taken place ; this is 

 probably due to the production of diffusible solids by autolysis of the cell 

 contents. 



In Experiments 81 and 139 yeast was employed which had been kept in 

 the cold room for three days. The yeast of 144 was a sample which had 

 been dried in the air at room temperature. The original percentage of total 

 solids in this dry yeast was 68 - 4 per cent. On immersion in 10 per cent, 

 alcohol the yeast absorbed liquid very quickly, and eventually, after 20 hours, 

 50 grm. had increased to about 110 grm. Notwithstanding this large influx 

 of liquid, the diffusion factor is seen to be not widely different from the 

 normal. 



Sodium Chloride. 



This substance was taken as being a typical salt dissociated into its ions 

 more or less completely in dilute solution. Four experiments were made, the 

 results of which are given below. The salt was estimated in the liquid by 

 the method of Carius, the amount in the yeast being calculated by difference. 

 Preliminary experiments had shown that when 50 grm. of pressed yeast 



Table VIL— Diffusion of M/10 Sodium Chloride. 



No. 



Conditions. 





Liquid. 





P. 



Pi- 



K. 





Initial. 



Final. 



Initial. 



Final. 



60 



Allowed to stand 2 

 in cold store 



3 hrs. 



Total ... 

 NaCl ... 



100 -50 

 0-58 



101 -oo 

 0-54 



50 -00 

 nil 



49 -50 

 0-04 



0-11 



0-54 



-21 



61 



Allowed to stand 2 

 in cold store 



3 hrs. 



Total ... 

 NaCl ... 



100 -50 

 0-58 



100 -30 

 0-55 



50 -00 

 nil 



50 -20 

 0-03 



-08 



-55 



0-15 



64 



Allowed to stand 3 hrs. 

 at room temperature 



Total ... 

 NaCl ... 



100 -50 

 0-58 



104 -30 

 0-58 



50-00 

 nil 



46 -20 

 nil 





0-56 





65 



Allowed to stand 3 hrs. 

 at room temperature 



Total ... 

 NaCl ... 



100 -50 

 0-58 



101 -60 

 0-58 



50 -00 

 nil 



48-90 

 nil 





0-58 





