LABORATORY MANUAL OF PHYSIOLOGY. 



distilled water. What is the effect on the life and growth of the 

 plant ? 



Place a specimen in the dark for several hours. Examine for 

 starch by treating with iodine. Result ? Place some of this same 

 material in bright sunlight for several minutes. Examine for 

 starch again. Result ? 



II. FUNGI. 



Yeast. (Torula or Saccharomyces cerevisice). This plant, in 

 common with the other fungi, differs from the algae, which have 

 been studied, in not containing any chlorophyll. The algae, which 

 contain this pigment, are able to obtain their nutrition from the in- 

 organic constituents of their environment. The yeast, on the other 

 hand, in which this pigment is absent, is dependent upon organic 

 material for the processes of its metabolism. 



Practicum. Nutritive fluid for yeast (Pasteur's fluid). 



Potassium phosphate 2.0 grams. 



Calcium phosphate 0.2 " 



Magnesium sulphate 0.2 " 



Ammonium tartrate 10.0 " 



Cane sugar 150-0 " 



Water to 1000.0 " 



(a) Put a small quantity of fresh baker's yeast into some of the 

 above-described fluid and keep in a warm place. As soon as the 

 culture becomes frothy and cloudy it is ready for examination. 



(b) Place some of this mixture on a slide without a cover glass 

 and examine with a low power of the microscope. Note size and 

 arrangement of the cells. Place a cover slip on the specimen and 

 examine with a high power. What is the mode of union of the 

 cells ? Describe the structure. Make a drawing. 



(c) Stain a specimen with fuchsin. Treat another with iodine. 

 Is there any starch present ? 



(d) Sow some yeast in Pasteur's fluid and place in the incuba- 

 tor for several hours. Place another specimen in the cold for the 

 same length of time. Compare the growth in the two specimens. 



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