144 CARL R. MOORE 



It is possible that the differences of the male and female hair 

 coats of Steinach's rats were more pronounced than in the strain 

 used in these experiments.^ It is true that a slight difference can 

 be noted in normal healthy white rats of the same age. The 

 male hair coat appears slightly rougher, the hair being a little 

 more coarse than that of the female; this in a general way gives 

 a softer, smoother appearance to the female than to the male. 

 But this also is subject to so many variations that it is decidely 

 unsafe to use it as an indicator. The variation? at different ages 

 are considerable, and a slight metabolic disturbance also gives 

 entirely different appearances to the hair. Numerous instances 

 have been noted in which the female coat was rougher in appear- 

 ance than that of the male. Indeed, the writer has often found 

 it entirely impossible to choose the males and females from a 

 cage of normal and apparently healthy mixed rats by this means 

 alone. This being true, it would be entirely impossible to note 

 the changes in an intersex condition and to place properly these 

 changes as quantitative determiners of a modified sex condition. 

 If one were a decided advocate of the idea, it would be a simple 

 matter to record differences that would support the hypothesis. 

 It is possible, however, that Steinach's material showed greater 

 differences than the rats used for these experiments. 



In relation to mammary glands Steinach has already pointed 

 out the fact that rats offer very poor material for study of their 

 changes. The primordial teat is not produced in the male so 

 that little influence from the implanted gonad upon the primor- 

 dial mammary gland can be seen.^ 



Steinach ('12) has reproduced radiograms of feminized male 

 rats to show the difference in size of the pelvis between these and 

 normal or merely castrated male rats. These radiograms show 

 very clearly the comparatively small size of the pelvis in femin- 

 ized rats, but they also show, to a like degree, the reduction of 



' Steinach seems to have used partly wild rats, partly tame (white) ones, and 

 crosses between these. 



^ Guinea-pigs afford much better material for study of possible changes in the 

 mammary gland due to internal secretion of gonads; experiments are now under 

 way on these animals and will be reported at a later date. 



