Correlation betiveen Ovaries, etc., in Rabbit. 423 



(1) Foetus extract was injected for 15 days into a virgin rabbit aged 

 5 months. The rabbit was then killed, when it was found that the ovaries 

 contained a few follicles apparently ripe or nearly ripe, and the uterus a 

 few glands. The mammary development was limited to ducts which were 

 about 1 cm. long (fig. 1). 



(2) In another virgin rabbit of the same age and treated identically the 

 ovaries showed a degenerate follicle and a few follicles apparently ripe. 

 The uterine glands were slightly developed, and the ducts of the mammary 

 glands were fairly well developed, being about T|- cm. long. 



(3) Another virgin rabbit of the same age and treated identically gave 

 similar results to the last (No. 2). 



(4) A virgin rabbit, aged 5 months, was allowed to undergo a sterile 

 copulation with a buck from which a portion of each vas deferens had been 

 removed. It was killed 12 days after copulation. Contrary to expectation, 

 no corpora lutea were found in the ovaries, but there was one large follicle. 

 The uterus contained a few glands, and the ducts of the mammae were about 

 \ cm. long. 



(5) A virgin rabbit, 7 months old, was allowed to undergo a sterile coition 

 with a vasectomised buck. It was killed 12 days afterwards. As in the 

 last case (No. 4) no corpora lutea were found, but protruding follicles were 

 present. The uterus had a few glands. The ducts of the mammary glands 

 were well developed, being about 2\ cm. long. 



(6) Another virgin, 7 months old, was allowed to undergo a sterile coition. 

 It was killed 24 days later. There were no corpora lutea, but many pro- 

 truding follicles, and the mammary ducts were about 2 cm. long. 



It is thus seen that prior to ovulation the mammary development was 

 limited to a slight cell proliferation in the ducts, and that the growth was 

 not augmented by the injection of boiled foetus extract. On the other hand, 

 after ovulation (at least in the rabbit) definite mammary hypertrophy sets 

 in, as will be described below. 



Probably in the majority of mammals ovulation takes place spontaneously 

 during oestrus. This is the case in the mare, the cow, the sow, the sheep 

 (at least ordinarily), and the bitch. On the other hand, in the rabbit, the 

 cat, and the ferret, ovulation, as a general rule, only occurs as a result of a 

 stimulus set up by sexual intercourse. To which of these categories man 

 belongs is still an open question. 



It is generally believed that whereas the corpus luteum verum (or corpus 

 luteum of pregnancy) and the so-called corpus luteum spurium (which is 

 developed when pregnancy does not follow ovulation) are identical by origin, 

 the structure formed after ovulation does not hypertrophy to the same 



VOL. LXXXVII.— B. 2 K 



