1893.] MICROSCOPICAL JOURNAL. 17 



Experiments witli Yeast— A Biological Study. 



By J. W SMITH, 



ST. PAUL, MINN. 



A small bit of yeast from a cake of compressed yeast, sus- 

 pended in a drop of water on the glass slide of the microscope 

 and examined under the low-power glass, was found to be uni- 

 form in composition. The high power revealed the form of the 

 minute globules of which it was composed. These globules are 

 unicellular, consisting of protoplasm contained in a cell wall. 

 No nucleus was visible, but a vacuole was plainly seen. (Fig. i.) 

 This was the appearance of the mass. 



For the stud)? of the nutrition of yeast, Pasteur's fluid was the 

 basis of the experiments. Yeast in the solution 34 hours at the 



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temperature of the laboratory, was found to have grown by bud- 

 ding into such forms as those shown in Fig. 2. 



Experiment i — a. In water 5 hours, at the same temperature, 

 none were found to have more than one bud, and many none. 

 (Fig. 3-) 



Exp. I — b. In 80 parts water and 15 parts sugar, under the 

 same conditions, most of the cells were budded with a single bud. 

 (Fig. 4-) 



Exp. I — c. In all the ingredients of Pasteur's fluid but sugar 

 a few of the cells were budded, but not so many as in the former 

 experiment. 



Exp. I — d. In Pasteur's fluid 6 hours, 20° C, the parent cell 

 was budded at each end, and in many cases the bud was budded. 

 (Fig. 5) 



The second series of experiments was also to test the food value 

 of various mixtures, but for a longer period of time, 27 hours rn 

 light at 18° C. 



