SECRETORY FUNCTIONS IN HUMAN PLACENTA 495 



thus in general giving them something of a meshy arrangement. 

 The nuclei are clear and have in themselves a more or less con- 

 spicuous nuclear network, with one or two nucleoli. 



In figure 2 the syncytium layer closely resembles figure 1 in 

 structure, though the plastosomes contained therein differ from 

 one another in their shape, arrangement, and number. These 

 two figures show the simplest structure of the syncytium layer. 



In figure 3 the plastosomes are generally faint and quite 

 scattered; in the protoplasm there are some dark-colored gran- 

 ular bodies of difi"erent sizes and a small number of vacuoles; 

 the smaller granules are somewhat dark in color and are gener- 

 ally found very near the surface, viz., the brush-like border, 

 whereas the larger ones are light-colored and are found in other 

 parts of the layer. The vacuoles are found close to the Lang- 

 hans' layer. The nuclei are irregular in shape, and besides the 

 nuclear network there are one or two nuceoli. 



In figure 4 the plastosomes are generally found in the 

 deeper layer, i.e., close to the Langhans' layer, and they are 

 comparatively small in number. On the contrary, however, 

 plenty of dark or yellowish dark-colored granules occur 

 conspicuously all over the layer, the deeper colored ones being 

 generally superficial. Undoubtedly, granular bodies of this 

 kind have grown up from the dark-colored granules in a con- 

 spicuous manner such as I have shown in figure 3 above, and 

 they are very frequently met with elsewhere in the other parts 

 of the syncytium layer. And, moreover, granular bodies of 

 a similar kind are found, as will be seen in the following state- 

 ment, not only in the syncytium layer, but also commonly in 

 other cell groups. These granular bodies are, of course, extreme- 

 ly varied in their size, quantity, and color; however, since 

 they have a common affinity to certain chemical and coloring 

 matter, e.g. osmic acid, iron-alum-haematoxylin, and acid fuch- 

 sin, etc., I have followed, for the sake of brevity, the precedents 

 of many histologists in including all these granular bodies under 

 the name of 'lipoid' granules. In this figure there is, moreover, 

 only one vacuole close to the brush-like border. The nuclei are 

 less conspicuous in their network, the chromatin forming 



