500 GENCHO FUJIMURA 



remarkable manner on the seventeenth or eighteenth day after 

 pregnancy, reaches the maximum of growth at the end of the 

 first month, and from the second to the third month it seems, 

 although not very conspicuously, more or less reduced in thick- 

 ness, but after the fourth month it suddenly becomes thinner, 

 and simultaneously its structure becomes simphfied, and in the 

 seventh month it will altogether atrophy and remain simply in 

 the form of a thin membrane like an endothelium. Moreover, 

 in the last two months the layer will disappear in some places 

 and will be noticeable only as a discontinuous thin cover. In 

 other words, this layer, excepting in the early stage of pregnancy, 

 always decays and goes out of existence in inverse proportion 

 to the growth of the embryo, and this is the very point which 

 should engage the careful consideration of those who are inter- 

 ested in the functions of this layer. 



2. The Langhans' cells (figs. 13 to 26) 



The Langhans' cells have in general distinctly clear bodies, 

 and are distinctly bordered wdth a thin membrane (pericula?) on 

 the surface. Their sizes, shapes, and structures are extremely 

 varied; on examination of the smallest cells (figs. 13 to 16 and 

 7, 8 and 10) it will be found that they are either round like a 

 ball or oval-shaped, with foamy nuclei of corresponding shapes 

 inside. The structures of the cell bodies consist of quite struc- 

 tureless stroma and a large quantity of plastosomes, of which the 

 latter are rod-shaped in several lengths, and are usually dis- 

 tributed all over the cells, though sometimes they crowd together 

 on one side of the cells. There is occasionally a small oval- 

 shaped body somewhat dark in color close to one side of 

 the nucleus, which might possibly belong to Meves' so-called 

 'Centrotheca;' it, however, lacks a centriole within (fig. 13). 

 Within the nuclei there are generally one or two conspicuous 

 nucleoh, and in most of the cases it is difficult to discern the 

 nuclear network. In the large sized cell bodies (figs. 17 to 19 

 and 2, 3, 9, 11 and 12) we always find either a small quantity 

 of fipoid granules or vacuoles. The lipoid granules are nearly 

 the same in size, and, though small in number, they are scattered 



