SECRETOEY FUNCTIONS IN HUMAN PLACENTA 533 



/. All vacuoles gradually unite, and it appears that they 

 possibly make a kind of canal system running irregularly and 

 crosswise within the syncytium layer, and some of them distinctly 

 open their mouths in various places on the surface of the 

 syncytium layer, thus it is apparent that their contents, their 

 secretions, are drained out into the maternal vessel of the inter- 

 villous spaces. And, as is seen in figure 11, the blood corpus- 

 cles which are noticeable within the syncytium layer may be 

 rightly taken for the mother's corpuscles which have accidentally 

 gone into the canal system mentioned above, which would in 

 turn prove the existence of the latter. 



g. The secreting function is at work from the beginning of 

 pregnancy to the end of the fourth month, though it is most 

 active in the second and third months. 



2. The 'phenomena of secretion of the La7ighans^ cells 



The protoplasm in the Langhans' cells which are still small 

 and should be deemed comparatively young contains plastosomes 

 only (figs. 13 to 16); however, as the cells reach a certain size 

 the lipoid granules appear (figs. 4, 11, 12, 17, and 22). The 

 latter have developed from extremely small granular bodies such 

 as are visible in figures 9 and 21, and their number is not very 

 large; the vacuoles appear in a very conspicuous manner, and it 

 seems that these have also grown into what they are compara- 

 tively speedily from a very minute form, it being clear that the 

 larger of them have been brought into being by the agglu- 

 tination and joining together of some of the vacuoles. And, 

 while the secreting process is in progress, it seems that lipoids 

 play a directly essential part; how they change their quality 

 and liquefy from the periphery, and thus gradually pass into 

 vacuoles as in the syncytium layer, can be very clearly seen 

 in figures 12, 23, and 24. The loss of lipoids which keeps going 

 incessantly by such vacuolation is made good by fresh forma- 

 tions elsewhere, and thus, the same process being repeated, the 

 vacuoles go on growing in number and size simultaneously as 

 the cell appears more and more to increase in its capacity. 



