PHYSIOLOGICAL PROPERTIES OF GONADS 367 



that of normal females. The increase in weight in female rats, 

 into which a testis has been grafted, is then due only to the re- 

 moval of the ovary, and not to a secretion from the implanted 

 testis, as Steinach has maintained. The same criticism holds 

 good for body length of the animal. A table of weights com- 

 pounded from a series of weighings made on eight animals of the 

 same litter,^ in five of which transplanted gonads of the opposite 

 sex than the host were growing, shows clearly that little if any 

 dependence can be placed on the weight of an animal as an indi- 

 cation of its sexual nature. In the same paper criticisms were 

 offered relative to other indicators of the sexual nature of the 

 animal, but my observations upon the psychical influences of the 

 implanted gonads substantiate those of Steinach to some extent. 

 Some of the female rats in which a part of the testis was suc- 

 cessfully grafted behaved in a typical manner. And some of the 

 males in which ovarian grafting was successful exhibited unmis- 

 takable maternal behavior toward the young. 



It must be emphasized, however, that many pitfalls beset 

 attempts to analyze the sexual nature of either a rat or a guinea- 

 pig by its behavior, and only the most obvious reactions should 

 be used as an indication of the effects of a sex-gland graft. 



Sand ('20), working with guinea-pigs, substantiated many of 

 the claims of Steinach, but disagrees with the latter that an antag- 

 onism exists between the sex glands. He was successful in im- 

 planting an ovary into the substance of a testicle and claims that 

 he could notice momentary changes in the psychical nature of 

 the animal even within the course of a single hour; it is first a 

 female in behavior and immediately afterward is a male. He 

 was not able to obtain growth of a subcutaneous graft of a sex 

 gland if the glands of the host remained intact, and his somewhat 

 elaborate hypothesis explaining this failure is interesting if not 

 essential. 



In 1920-21 the writer published the results of many operations 

 in which the portions of the sex gland of the rat were grafted into 

 an animal of the opposite sex, without the removal of the sex 



2 See Moore, '19, page 142 (table). 



