94 Society for Experimental Biology and Medicine. 



decidual tissue begins to take place normally, other stimuli are also 

 able to call forth the production of decidual nodules. At the pres- 

 ent stage of the investigation I do not, however, wish to deny pos- 

 itively that a brief contact of the ovum with a wound of the uterus 

 or with the inverted mucous membrane of the uterus is necessary 

 for the production of decidual nodules. Between the third and 

 fourth week after impregnation such nodules become necrotic. 

 They resemble small tumors which originate under chemical stim- 

 ulation, and are of a transitory character because the stimulus is 

 transitory. They might be called benign deciduomata and be 

 classed among that variety of new growths which I designated as 

 transitory tumors and of which the corpus luteum might serve as 

 a prototype. Among the animals experimented upon in the first 

 three days of pregnancy, only once a deciduoma was found. 



These experiments may also be of interest in so far as they seem 

 to show that under ordinary conditions it is not possible to produce 

 an abdominal pregnancy in the guinea pig by various injuries of the 

 uterus ; although it may be assumed that under the conditions of 

 the methods of experimentation adopted by me, the ovum had, in 

 many cases, easy access to the abdominal cavity. In no instance 

 did the peritoneal cavity show any change in the course of these 

 experiments. We may, therefore, assume that the entrance of the 

 ovum into the abdominal cavity is usually not sufficient to pro- 

 duce an abdominal pregnancy. 



65 (208) 



The effect of light on the staining of cells. 

 By LEO LOEB. 



[From the Laboratory of Experimental Pathology, University of 



Pennsylvania.'] 



Former studies of the structural changes in blood cells, 

 especially of the behavior of cell granules under the influence of 

 different external conditions, made it desirable to investigate the 

 behavior of cells in different staining solutions, especially in solu- 

 tions of vital stains. In the course of various investigations, it 

 was found that solutions not only of eosin but also of other stains, 

 as neutral red, affect the cells very differently in light and in dark. 

 That eosin and other fluorescent substances are much more poison- 



