114 CARNEGIE INSTITUTION OF WASHINGTON. 



the body and entered the operated tube instead of passing out through 

 the free passage existing between the ovary and the uterus on its 

 original side. However, these anomaUes are rare and can not be 

 viewed as the rule in cases of tubal pregnanc3^ Much more commonly 

 associated with tubal pregnancy is a chronic inflammation followed by 

 adhesions and kinking of the tube. This has been repeatedly observed, 

 but it is difficult to establish etiological association between adhesions 

 on the outside of the tube with the arrest of an ovum within its lumen. 



In case the ovum becomes well implanted within the middle of the 

 tube and ruptures into the broad ligament, conditions are brought about 

 which favor the development of a normal embryo. Rupture on the 

 free side of the tube throws the embryo into the peritoneal cavity and 

 therefore usually terminates its life. The same is true when the 

 implantation takes place near the uterus. Here the tube distends with 

 difficulty. The ovum burrows into its thick wall and usually passes 

 straight through into the peritoneal cavity. 



AMienever the degree of alteration in the tube wall is pronounced 

 and is accompanied by marked infection, the ovum does not implant 

 itself well and consequently the embryo does not develop normally, but 

 becomes atrophic and degenerates. The more severe this process the 

 more pronounced is the reaction upon the ovum; or in case it begins to 

 develop normally, excessive hemorrhage around the ovum detaches the 

 chorion from the tube and strangulates the embryo within. It dies 

 immediately, showing no tendency to grow in an irregular fashion. 

 Later it disintegrates. 



Pathological ova without embryos are very frequently encountered. 

 They have been found in 59 per cent of our selected cases, while only 2.7 

 per cent of specimens obtained from the uterus fall under this heading. 

 But, as Werth also admits, the figures in both groups are probably much 

 too small, as no doubt many of the earlier specimens were lost or over- 

 looked. We have no adequate data regarding the number of ova which 

 disintegrate early, but the study of comparative embryology warrants 

 the conclusion that many young ova degenerate and disintegrate. 



Pathological embryos in the tube, as well as those in the uterus, no 

 doubt give rise to merosomatous monsters which are not of hereditary 

 character. Studies relating to this subject are still under way. 



In addition to the work on pathological embryology, various studies 

 have been published which will be described in the following order: 

 cytology, development of the nervous system, development of the 

 blood-vessels, development of the lymphatics. 



Our cytological studies include further investigations on mitochondria 

 by E. V. Cowdry, W. H. and M. R. Lewis, and J. Duesberg. The 

 behavior of cells in the presence of vital stains and the character of the 

 macrophage cell have been investigated by H. M. Evans, K. J. Scott, 

 W. B. Martin, and C. R. Essick; M. R. Lewis has grown muscle-cells 

 in tissue cultures and has studied the rhythmical contraction of such 



