SECKETORY FUNCTIONS IN HUMAN PLACENTA 497 



In figure 7 the syncytium layer is extremely thick, and it is 

 difficult to demonstrate the plastosomes. Lipoid granules of 

 extremely varied sizes are found in large quantities. These 

 granules are irregularly arranged, and they tend more or less 

 to occur in groups; certain lipoid granules make their appear- 

 ance as contents of vacuoles, in which case the granules always 

 have a clear halo around them, as if they constituted the nucleus 

 of the vacuoles. Such images are frequently met with not only 

 in the syncytium layer, but also in other cell groups and, since 

 they are worth recognizing as very clearly indicating the relations 

 which exist between the lipoid granules and the formation of 

 vacuoles, the reader's special attention is hereby drawn to this 

 point (vide the left-hand side of this figure). The vacuoles are 

 abundant, and their sizes and shapes are quite irregular and, as 

 will be seen in the middle part of this figure, a great number 

 of them are joined together at some places without boundaries 

 being noticeable between them. From the existence of such 

 images I am led to infer that an extraordinarily large vacuole 

 is in general the outcome of minor vacuoles being agglutinated 

 and joined to one another. In this way, it seems that the 

 vacuole's which have grown up into tremendous sizes finally 

 rupture toward the surface, as it will be seen in the present 

 figure that such vacuoles open up and connect directly with the 

 intervillous spaces, clearly supporting the interpretation that I 

 have given above. 



In figure 8, it is in general extremely deficient in its character- 

 istic dark-colored protoplasm, but then there are all over the 

 layer numberless vacuoles of a very small size, which grow so 

 close to one another that they have exactly the appearance of 

 a beehive. Of these vacuoles some of the larger ones lie to- 

 gether close to the surface, while others, connected with one 

 another, mutually find their outlets to the surface through 

 comparatively large openings. Because of these openings the 

 surface of the syncytium layer, which is naturally level, becomes 

 very uneven and irregular. The lipoid granules are very few, 

 and no plastosomes are to be found. The nuclei are not only 



