Ovaries, Uterus, and Mammary Glands in Rabbit. 429 



A case of a rabbit which prepared a bed for a litter and secreted milk at 

 the termination of the pseudo-pregnant period has been recorded above. 

 Cases have also been reported by various observers of similar instincts in 

 bitches, which have been described as making preparations for parturition and 

 secreting milk nine weeks after coition although they had failed to become 

 pregnant. Thus Heape records instances of bitches which had been " lined " 

 but had " missed " having pups, yet had secreted milk at the time when they 

 were due to whelp, in sufficient quantity to admit of their rearing litters 

 belonging to other bitches. Cases have also been recorded by Noel Paton. 

 Moreover, several such cases of bitches which did not conceive but yet have 

 afterwards yielded milk have been recently reported to the authors. 



It is suggested that in these animals the building up of the mammary 

 glands and the resulting secretion of milk may have taken place in response 

 to a stimulus arising in corpora lutea which developed after oestrus and 

 possibly persisted for an abnormal length of time. If this explanation 

 is correct it is clear that no essential distinction can be drawn between the 

 corpora lutea of pregnancy and the periodic corpora lutea in regard to their 

 functional relation to the mammary glands. 



Our observations lend no support to the theories of Starling and Lane- 

 Claypon, Foa, Biedl and Koenigstein, who have supposed that the mammary 

 glands are built up under the influence of a hormone arising in the foetus, 

 neither are they confirmatory of the view put forward by Halban, who 

 regards the placenta as a factor in mammary growth. Our experimental 

 results are, at first sight, somewhat difficult to reconcile with the facts 

 observed by Ott and Scott, and Schafer and Mackenzie, who found that 

 corpus luteum extract (like that of pituitary) when injected into the 

 circulation has an immediate galactogogue action. It must be borne in 

 mind, however, that the sudden injection of considerable quantities of corpus 

 luteum extract into the circulation is not a process which occurs in nature, 

 and consequently we might expect its effect upon the mammary tissue to be 

 different from that of small quantities of the problematical hormone when 

 continuously secreted over a long period. 



The Effect of Hysterectomy witliout Ovariotomy. 



Experiments were also undertaken to ascertain whether or not the uterus 

 is an essential factor in mammary growth. As already mentioned, Ancel 

 and Bouin have expressed the opinion that in the later stages of pregnancy 

 the myometrial gland of the uterus is an exciting cause in mammary 

 development. It occurred to us that it was possible that the uterus might 

 also be an essential factor in bringing about mammary development in the 



