202 INTERNAL SECRETIONS OF THE OVARY 



Cyclic variation in the spontaneous activity of the uterus. It is 

 well known that the uterus of the guinea-pig during cestrus 

 shows remarkable spontaneous contractions, which make the 

 organ at that time useless for the standardization of drugs. The 

 cyclic variation in spontaneous contraction of the uterus has 

 been studied in the rat by Blair (68), Frank and co-workers 

 (222), and Clark, KnausandParkes (120); andin thesow by Keye 

 (321), Corner (124), Seckinger (554), and Wislocki and Gutt- 

 macher (642). The general conclusion reached is that during 

 dioestrus the uterus shows rapid feeble contractions, while 

 cestrus is characterized by fewer but much more powerful con- 

 tractions. Seckinger, however, obtained rather contrary 

 results from the Fallopian tube, and Clark, Knaus, and Parkes 

 found the variation in the rate of conduction of a contraction to 

 be the most significant factor. Frank and his co-workers (222) 

 state that after ovariectomy the uterus shows contractions 

 similar to those occurring during dioestrus. Knaus (327-9) has 

 extended this type of work to the rabbit uterus during preg- 

 nancy. This author has carried out very careful experiments, 

 in which any possible effect of enlargement of the muscle fibres 

 on the uterine properties was eliminated by the use of a sterilized 

 cornu containing no foetuses. His results show that during the 

 first half of pregnancy the uterus is practically inactive owing 

 to loss of contractihty, while during the second half there occurs 

 a continuous rise in spontaneous activity, which reaches a 

 climax at parturition. Knaus ascribes this comparative 

 quiescence of the uterus during most of gestation to the action 

 of the corpus luteum. 



Direct effect of ovarian extracts on uterine contraction. Acting 

 on the idea that the greater amplitude of the spontaneous 

 contractions of the uterus during oestrus is due to the influence 

 of oestrin, various workers have endeavoured to reproduce the 

 effect artificially. This has been attempted in two ways, {a) 

 injection of the ovariectomized or dioestrous female before 

 preparing the isolated uterus, (h) subjection of the isolated 

 uterus to oestrin. Frank and co-workers (222) and Brouha and 

 Simonnet (101-2) state that the contractions of the uterus of the 

 ovariectomized or dioestrous animal can be altered to those of 

 oestrus by preliminary injection of the animal. Fellner (192), 



