222 CAREY P. McCORD AND FLOYD P. ALLEN 



Effect of pineal extract upo7i unstriated muscle 



Aqueous extracts of fresh pineal glands were tested accord- 

 ing to the method of Dale and Laidlaw (13) upon isolated 

 strips of guinea-pig uterus. The extract produced a typical 

 though feeble contraction of the uterine muscle. Three cc. 

 of a 20 per cent pineal extract was roughly equivalent in activity 

 to 0.004 cc. of a 20 per cent pituitary extract. Thus pineal 

 extracts stimulate certain smooth muscle cells as well as pigment 

 cells to contraction. This similarity of action goes far to con- 

 firm Spaeth's hypothesis that the melanophore is a type of 

 smooth muscle cell. 



COMMENT 



Many acceptable evidences associate the pineal gland with 

 an earlier optical function. In the reptilian stage of evolution 

 this parietal eye probably attained to its highest development. 

 In the embryos of certain lizards (Lacerta agilis) the typical 

 eye structure is still evident, but in no form living at the present 

 time does the pineal gland retain an ocular function, of high 

 order (14). 



The color changes in forms are obviousl}^ in adjustment to 

 environmental conditions. The eye is the essential controll- 

 ing factor in this adjustment. When in blinded animals cer- 

 tain definite changes in pigmentation still occur, on theoretical 

 ground it is tenable to assume that the pineal body retains suf- 

 ficient ocular mechanism to exert its influence upon the pigment 

 cells. This is the hypothesis suggested by Fuchs (10). Laurens 

 has established experimentally that such an activity on the 

 part of the pineal is highly improbable (11). Accepting the 

 contentions of Laurens, it is the gist of our work that while the 

 pineal does not act in the role of its ancient ocular function, it 

 contains within itself an active principle capable of inducing 

 pigment changes independent of and wholly apart from environ- 

 mental conditions. The pineal pigment changes dominate and 

 appear despite environmental conditions tending toward the 



