DEPARTMENT OF EMBRYOLOGY. 81 



month of intrauterine life. Among the interesting details of development 

 that were discovered, mention should be made of the following: The umbilicus 

 shifts to a relatively higher and the nipples to a relatively lower position on 

 the trunk in the course of growth. Compared to the height of the trunk, the 

 limbs grow very rapidly until the end of the fifth month, whereafter their 

 growth slows down, so that at birth the extremities are again relatively shorter. 

 The forearm grows faster than the upper arm and the leg faster than the 

 thigh; in negroes both forearm and leg are relatively longer than in whites. 

 The thumb becomes relatively shorter with advance in development, but, as 

 might be expected, it is at all stages slightly longer in whites than in negroes. 

 The hand, as well as the foot, is relatively broader in early than in late fetal 

 life, and both are broader in whites than in negroes. In man the great toe 

 becomes relatively longer and the other toes relatively shorter during develop- 

 ment, whereas in these points the ontogeny of other primates behaves in just 

 the opposite way. As for the head, it may be said that the cephalic index 

 decreases with advance in development. The face grows faster than the 

 cranial part of the head and is larger in negroes than in whites. 



PHYSIOLOGY OF REPRODUCTION. 

 Cyclic Changes in the Tubal Epithelium. 

 The interesting observation has been made by Dr. F. F. Snyder that, 

 during the oestrous cycle of the pig, the epithelial tissues of the Fallopian tube 

 pass through a series of alterations closely resembling those exhibited by the 

 epithelium of the uterus, which were described by Dr. Corner and mentioned 

 in my last report. During oestrus, while the ova are passing through the tubes 

 (first three days after ovulation), the epithelium is more than twice as high 

 as during the period of implantation in the uterus (second week after ovula- 

 tion), and during the third week, with the return of oestrus, it gradually 

 regains its maximum height. While the epithelium is highest, the under- 

 lying stroma shows its participation in the process by its swollen and edema- 

 tous condition. Coincident with this periodic rise and fall in the height of the 

 epithelium, there is an alternate appearance and disappearance of the char- 

 acteristic cytoplasmic projections of the non-ciliated cells, the projections 

 disappearing as the epithelium becomes higher. Just why these changes 

 should occur in the tubes remains obscure. In the uterus it seems probable 

 that they take an active part in the mechanism of implantation, and it is 

 possible that the tubal reaction is merely due to the embryological fact that 

 the tubes are derived from the same primordium (Miillerian ducts) that forms 

 the uterus. Compared with the ovarian phases, the decrease in height of the 

 tubal epithelium and formation of the cytoplasmic processes is synchronous 

 with the growth and full development of the corpora lutea, and in the event 

 of pregnancy the epithelium remains in this state, further alteration apparently 

 being inhibited. Dr. Snyder finds that the ciliated cells of the tubal epithelium 

 show no alteration, either in distribution or activity, at any period of the 

 cestrous cycle, which is further evidence that they play no role in the migration 

 and implantation of the ova. 



Cyclic Changes in the Smooth Muscle of Uterus and Tubes. 

 Supplementing Dr. Corner's studies on the cyclic changes in the ovaries 

 and uterus of the sow, Mr. J. D. Keye, for the uterus, and Mr. D. L. Seckinger, 

 for the Fallopian tube, have found that periodic variations occur in the spon- 



