PINEAL GLAND FUNCTION 213 



ing experiments on these animals. Concerning the pigment 

 altering tissues he states: 



After five weeks feeding, those (Tadpoles) fed on adrenal cortex be- 

 came much lighter than those fed on adrenal medulla or any other food. 

 This difference in color became more evident as the experiment pro- 

 ceeded, until the cortex-fed tadpoles had an extremely light, greenish 

 yellow tint. The spleen and thymus fed tadpoles became extremely 

 dark during the course of the feedings. Those fed on Hver developed 

 a dark greenish color, those on ovary a yellowish color. 



The type of pigment variation observed by Gudernatsch is 

 obviously distinct from that observed by us. In his animals 

 the pigment alteration was slow in appearing and persistent. 

 In ours the change appeared early in life, occurred sharply in 

 relation to feeding, was cyclic and transient. 



After the tenth day of larval life pigment changes were always 

 evident after every feeding of the pineal tissues and the animals 

 continued to react until their forelegs protruded. Sufficient 

 blanching of the bodies occurred within thirty minutes after 

 pineal feedings to differentiate these colonies from their con- 

 trols. A maximum condition of translucency was attained in 

 about forty-five minutes, and three to six hours later restoration 

 to the original color was complete. The difference was first 

 noticeable in the region about the eyes due to the absence of 

 larger viscera. It can be demonstrated, however, that the 

 reaction occurs simultaneously over the whole body. At the- 

 height of the reaction the integument was so transparent that, 

 the brain, the olfactory tracts, the kidneys, the beating heart 

 and the intestines were all clearly visible thi-ough the dorsal' 

 body wall. 



Figures 1 and 2 are drawings of a single tadpole just prior 

 to and forty-five minutes after feeding pineal material. The 

 darker portions in 2 are due to the denser viscera, the pigment 

 conditions being the same over the entire animal. 



Photography fails to give a true picture of this phenomenon 

 but since actual photographs are more valuable as exact evi- 

 dence than drawings figures 3 and 4 are here included. These 

 are respectively photographs of the same group of tadpoles 



