THE EFFECT OF SOME FOOD HORMONES AND 



GLANDULAR PRODUCTS ON. THE RATE OF 



GROWTH OF PARAMECIUM CAUDATUM. 1 



MARY H. CHAMBERS. 



The animal body is adjusted to live upon plant or animal 

 tissue. It is generally accepted now that the adequate diet 

 must contain more than protein, carbohydrate, and fat, namely, 

 an accessory factor or vitamin. Recent investigations upon 

 dietaries of infants have shown the importance of some of the 

 accessory factors. Hopkins (1912) added yeast to a diet of 

 purified food stuffs and found that it accelerated the growth of 

 rats. The same result was obtained later by Funk and Macallum 

 (1915). More recently Osborne and Mendel (1917) have shown 

 that the addition of yeast to the ration not only causes an in- 

 crease in rate of growth of rats, but it acts as a stimulus to the 

 appetite, and when removed from the diet growth ceases and 

 decline ultimately follows. As yeast supplies a definite sub- 

 stance for growth so also potato juice acts as a corrective in 

 cases of malnutrition. With these results in mind a series of 

 experiments was undertaken to determine whether or not ex- 

 tracts of yeast and potato juice added to the diet of Paramecium 

 produced any marked effect on the rate of division which accord- 

 ing to Calkins (1902) is the index to vitality. The investigations 

 were carried on under the direction of Dr. Florence Peebles, 

 to whom the writer is indebted for suggestions and assistance. 



A first set of experiments was made upon a pure line of Para- 

 mecia which had been maintained for several months on a diet 

 of malted milk. 



The solutions of yeast and potato which were employed were 

 I per cent., and were made with distilled water. There were 

 two methods of preparation with each. According to the first 

 method the compressed yeast cake was merely dissolved in 

 water, in the second, the yeast was first ground in order to allow 



1 From the Biological Laboratory, Bryn Mawr College. 



82 



