THE REPRODUCTIVE GLANDS 499 



characters. Such animals show less vigor and less muscular power. Sterili- 

 zation of the male without removal of the gonads is not followed by the usual 

 loss of vigor and of the typical male form and characteristics. This is ascribed 

 to the preservation of the testis which is thought to produce internal secretion 

 reacting through the nutritional processes of the body. 



b. The Ovaries. The ovaries not only possesses the germ cells, the ova, 

 but their structure is characterized by other types of cells the interstitial, 

 stroma, and f ollicular cells. When a graafian follicle ruptures and discharges 

 its ovum, cells rapidly grow and fill the cavity forming the corpus luteum. 



The surgical removal of the ovaries results in disturbance of the periodic 

 menstrual phenomenon, not because of the loss of the ova, but because the 

 secretin fails which maintains the normal periodic reactions of the uterus. 

 There are also in the human disturbances in nutrition from this cause, i.e., 

 a decrease in oxidations, tendency toward obesity, marked nervous symptoms, 



. FIG. 321. The galactagogic action of involuting uterus of the cat after intravenous 



injection of saline extracts. First tracing from above, blood-pressure; second, drops of 



ulk from a hollow needle inserted into a mamma; third, drops from a wick inserted into 



two mammas that have been split open to remove the effect of the contractions of the muscles 



of the gland. (Mackenzie.) 



etc. , These symtoms are reduced or entirely disappear on grafting a portion 

 of the gland, and the disturbed menstruation becomes regular again. Human 

 ovaries have been transplanted to patients after previous ovariotomy with a 

 recovery of normal body functions and improvements in health. Experi- 

 ments by Lowey and Richter indicate that oxidations in the body are greatly 

 increased on feeding ovarian extract to ovariotomized animals. Removal 

 of the ovaries of hens leads to a loss of feminine characters, i.e., the develop- 

 ment of spurs, cock-like comb and wattles, hackle, etc. Castrated female 

 ducks are also said to develop male-like characters. Guthrie suggests that 

 this may be " an unmasking of characters," since we do not know the asexual 

 type in the higher animals by any positive evidence. 



