SECRETORY FUNCTIONS IN HUMAN PLACENTA 499 



shaped and equally deep-colored as these which are found in 

 figure 10. There are few lipoid granules to be found, and they 

 exist for the most part in the superficial layer, scattered here 

 and there. What is especially worth noting is that there are red 

 blood corpuscles in the protoplasm between these vacuoles (vide 

 the left-hand side of the figure). The nuclei are oval-shaped, 

 and the chromatin is very peculiarly arranged, its outward 

 appearance resembling the shape of a chrysanthemum. In the 

 center there is a nucleolus, and it must be noted that a nuclear 

 condition of this kind is generally very rare. 



In figure 12 the protoplasm is glutted with numberless vacu- 

 oles, and it is for this reason remarkably foamy in appearance. 

 The vacuoles are of two sizes, of which the smaller ones are 

 mostly located in the deeper portion and make a somewhat 

 continuous layer, though in other parts there are to be found 

 some of these smaller-sized vacuoles also. The larger vacuoles 

 are crowded together in the middle part of the layer, and some 

 of them burst forth onto the surface, while others make their 

 appearance in the innermost layer close to the Langhans' cells. 

 The plastosomes are quite uniform in shape with those illus- 

 trated in the preceding figure, and they are all found in the pro- 

 toplasm between the vacuoles. The lipoid granules are nearly 

 of the same size and are found at several places, some of them 

 with the halos distinctly described. The nuclei appear to be 

 somewhat smaller in size, but there are no remarkable changes 

 in their structure. 



These structural conditions in the syncytium layer which I 

 have illustrated and described above can be detected at almost 

 any time and place at the different periods from the first month 

 of pregnancy to nearly the fourth, and, therefore, there is no doubt 

 that these structural changes cannot be taken as a measure to 

 tell the precise time of pregnancy. At no time after the fourth 

 month of pregnancy can we detect the plastosomes. . The lipoid 

 granules and vacuoles reach their maximum growth from the 

 second to third month of pregnancy, and after the fourth month 

 they gradually begin to decrease, entirely disappearing after 

 the seventh month. The syncytium layer comes in sight in a 



