26 EXPERIMENTAL GENERAL PHYSIOLOGY 



(2) Draw a careful figure of all forms studied, making the figure 

 large enough to show the details of structure clearly. Indicate in 

 the 'figure the location of the chlorophyll. If a nucleus or other 

 prominent mass is seen within the cell, locate it carefully in the 

 drawing. 



(3) Note carefully whether or not the organism moves. If it does, 

 determine the cause of the movement and describe it minutely. 



II. THE YEAST PLANT. 



The yeast plant (saccharomyces) belongs to a fungi. The fungi 

 and the algae belong to the lowest sub-kingdom of plants the 

 Thallophytes which are characterized by the absence of root, stem, 

 and leaf. The student will remember that all the algse which he 

 has studied have possessed chlorophyll or green coloring matter. 

 This is true of the algse in general. The fungi, however, have no 

 green coloring matter. The toadstool is a fungus, and it is wholly 

 without the green color which most plants possess. The yeast plant 

 is a fungus and it has no chlorophyll. 



What is the work which the chlorophyll does for the green plants? 



How does the yeast plant get its living? 



Laboratory Exercises. 



1. Put a bit of fresh yeast about as large as the head of a pin 

 upon a glass slide, mix it with normal saline solution (0.6 per cent. 

 NaCl in aq. dest.) and study under high power. Draw and describe 

 the cells. The yeast reproduces by budding or gemmation. It 

 reproduces also by the formation of internal spores (ascosporse) 

 (Fig. 6). Let your figure show various forms and combinations of 

 cells. Is the protoplasm of the cells homogeneous or is it granular? 

 Is a reticulum visible under your microscope? 



2. Put a piece of fresh yeast about the size of a hazelnut into 

 30 c.c. of Pasteur's fluid, and stand this for a period of one hour 

 in an incubator kept at a temperature of 35 to 40 C. 



Pasteur's Fluid: 



Potassium phosphate ....... 2.0 grains. 



Calcium phosphate 0.2 



Magnesium sulphate . . . . . . . 0.2 



Ammonium tartrate 10.0 



Saccharose (cane-sugar) ....... 150.0 



Aqua q. s. ad 1000.0 



After a half or three-quarters of an hour remove the yeast from 

 the incubator and examine the mixture carefully. Note the rapid 

 escape of bubbles from the liquid. If the liquid be placed in a 



