PHYSIOLOGICAL PROPERTIES OF THE GONADS. 305 



cent, greater in length than the corresponding bone of the cas- 

 trated male. This actual difference, however, is minimized when 

 it is remembered that the total body length of the normal males is 

 approximately 6 per cent, greater than that of the castrated animal. 

 If we compare the length of the bones as percentages of total body 

 length, we find that each bone of the castrated animal is relatively 

 longer than the corresponding bone of the normal animal (length 

 of femur, as percentage of total body length, norm. 15.18 per cent., 

 castrated 15.73 P er cent- I tibia, norm. 16.44 per cent., cast. 17.18 

 per cent.; fibula, norm. 13.8 per cent., cast. 14.3 per cent. Since 

 the relative lengths of the bones are greater in the castrated ani- 

 mals, the conclusion is that castration favors slightly growth in 

 length of hind-leg bones. It must be emphasized, however, that 

 this increase is not marked and careful computation must be em- 

 ployed to make it apparent. It appears so insignificant that little 

 value is attached to it, and certainly the results are not in agree- 

 ment with those who maintain that castration results in a marked 

 overgrowth in bone lengths. 



Spaying. When the average bone length of the normal female 

 group were compared with those of the spayed female group a 

 decided difference in length was noted ; the bone length of the 

 spayed females was greater than similar bone lengths of the normal 

 females. The observed length differences were as follows: 

 femur, 2.4 per cent. ; tibia, 3.6 per cent., and fibula 3.9 per cent. 

 longer in spayed females than in normal females. When one con- 

 siders that the total body length of the normal female was 2.4 

 per cent, greater than the spayed female, it is apparent that the 

 relative length difference is greater than that of the observed 

 length. We may conclude from this data that spaying in the 

 guinea pig is conducive to greater lengths in hind-leg bones. 



A number of investigators have reported exaggerated bone 

 growth after gonadectomy, particularly in the absence of the testis. 

 Poncet ('03), presenting a resume of his own earlier experiments, 

 as well as those of Pirsche ('02) and others, maintains that castra- 

 tion is followed by a general increase in the size of the skeleton. 

 Observations on eunuchs, clinical cases of testicular atrophy, and 

 experiments on laboratory animals were cited. In reference to 

 the guinea-pig bones, he found an increase in length of 3 mm. for 



