44 



SCIENCE 



[N. S. Vol. XL VI. No. 1176 



thinner under the dissolving or digesting ac- 

 tion of the leucocytes. The congestion in the 

 uterus and vagina becomes still more pro- 

 nounced, giving rise to small blood masses or 

 hffimatomata beneath the epithelium. The epi- 

 thelium of the uterus is highly disorganized, 

 vacuolized and richly invaded by the leuco- 

 cjrtes, so that portions of it fall away en 

 masse, actually carrying with it in some cases 

 cells of the stroma. 



(d) The fourth stage is merely a continua- 

 tion or result of the activities of the third. 

 The falling away of the epithelial pieces and 

 stroma cells permits the escape of the small 

 hsematomata or blood knots, thus causing a 

 slight bleeding into the lumen of the uterus 

 and vagina. These traces of blood often give 

 a reddish aspect to the vaginal fluid. At this 

 same stage a regeneration process begins from 

 the necks of the uterine glands and also appar- 

 ently from the epithelial infoldings in the va- 

 gina, so that the lost epithelium becomes rap- 

 idly replaced almost before it has ceased fall- 

 ing away. 



The regeneration process in the guinea-pig 

 is very short, lasting only a few hours, from 

 six to twelve in all. 



Ovulation seems to occur spontaneously dur- 

 ing every heat period without exception. The 

 rupture of the follicles with the consequent 

 ovulation takes place about the end of the sec- 

 ond stage or the beginning of the third; that 

 is, during the presence of the thick cheese-like 

 vaginal fluid. 



During the dioestrum or intermenstrual 

 period there is very little fluid to be found in 

 the vagina. This scant fluid consists of 

 mucus in which are some atypical squamous 

 cells from the vaginal wall and many leuco- 

 cytes. A number of the leucocytes are old 

 but there are probably new ones arriving al- 

 most continuously from the wall of the vagina. 

 The only time at which the vagina seems to be 

 practically free of leucocytes is immediately 

 before and during the first and second stages 

 of the (Estrous period described above. 



A marked correlation exists between the 

 oestrous changes in the uterus and the develop- 

 mental cycle of the corpora lutea. When the 



corpora lutea are highly developed and ap- 

 parently active the mucosae of the uterus and 

 vagina show a normally vigorous and healthy 

 condition. While on the other hand, when the 

 corpora lutea begin to degenerate during the 

 second week after the "heat period" the 

 mucosae of the uterus and vagina also begin to 

 shown signs of degeneration and the process 

 of desquamation slowly commences. At about 

 two weeks after the last " heat period," when 

 the wholesale destruction of the mucosa be- 

 gins, the corpora lutea are almost completely 

 degenerated. The breaking of the Graafian 

 follicles occurs during the oestrus as a result 

 of a congestion which began in the theoa fol- 

 liculi at about the same time as the congestion 

 of the stroma of the uterus and vagina. And 

 finally when the regenerative growth of the 

 uterine mucosa sets in, the ovaries then pos- 

 sess new corpora lutea in an active state of dif- 

 ferentiation which were derived from the re- 

 cently ruptured follicles. 



It, therefore, might be imagined that the 

 secretion from the corpora lutea exerts a pro- 

 tective influence over the uterus and vagina 

 while the absence of this secretion permits the 

 breaking down and degeneration of the uterine 

 epithelium typical of the " heat period." 

 C. R. Stockaed, 

 G. N". Papanicolaou 



THE IOWA ACADEMY OF SCIENCE 



The thirty-first annual session of the Iowa 

 Academy of Science was held at GrinneU College, 

 Grinnell, on April 27 and 28. The opening meet- 

 ing was called to order on Friday afternoon by 

 President Stewart, of the State University. After 

 the transaction of preliminary business the presi- 

 dent delivered his annual address on "Eecent ad- 

 vances in physical science and the relation of the 

 Iowa Academy to scientific progress. ' ' Professor 

 Conard, of Grinnell, who had been the academy's 

 delegate to the tenth annual meeting of the Illi- 

 nois Academy of Science, gave a report of that 

 meeting. A number of papers of general interest 

 were read and the president announced that other 

 papers would be read before the appropriate sec- 

 tions, which were: 1, Geology; 2, Zoology and Bot- 

 any; 3, Mathematics, Physics and Chemistry. 



Professor B. A. MUlikan, of the University of 

 Chicago, was to have given the annual address, but 



