488 GENCHO rUJIMURA 



times, but a great majority of these researches were confined 

 to the development or general construction of the placenta, 

 and very few authors have given any special consideration to 

 the internal secretion of this organ nor have they closely examin- 

 ed the minute construction of the tissue elements or cells of the 

 placenta, Already Ahlfeld ('78) had noted the appearance of 

 vacuoles in the syncytium layer, and subsequently many authors 

 recognized it; however, regarding the thing itself and its physio- 

 logical significance, nothing definite has yet been stated. Gotts- 

 chalk ('90) deemed it a pathological product; Kossman ('92) 

 took it for a kind of degeneration, while Langhans ('92) inter- 

 preted it as ' Leichenerscheinung. ' Further, regarding the glob- 

 ules of fat in the same layer, demonstrations had already been 

 made by Pela-Leusden ('97) and Marschand ('98). Bonnet 

 ('99) deemed it a nutritious matter taken up by the embryo, 

 and in recent times authors have generally agreed in recogniz- 

 ing it as nutritious matter of the embryo taken from the mother's 

 blood. Others, among them Halfbauer ('05), Costa ('04 and 

 '05), and Bondi ('11), inferred that the appearance of this matter 

 must be due to the active functions of the cells, by which it is 

 assimilated and absorbed. On the other hand, however, Wolff 

 ('13), as per Letulle and Larrier as mentioned above, on com- 

 paring the granular body of the syncytium layer with the secre- 

 tory grains within the ordinary gland-cells, stated that both of 

 them were a similar production. This theory was subsequently 

 supported by Fraenkel, who was close to the deduction that 

 there might be existent a certain secretory relation in the granu- 

 lar body of the syncytium layer. In short, the histological 

 studies of this subject up to now have been confined, as men- 

 tioned above, to the construction and, consequently, the functions 

 of the syncytium layer only, and there are even many defects 

 in the studies and some resultant weakness in the point of the 

 arguments, and no one can say that the opinions agree. Al- 

 though there are some authors who recognized the internal secre- 

 tory functions of the placenta, yet, since their arguments are 

 based on a single part of the organ, viz., the syncytium layer, 

 it must be stated that on the whole the basis of histological 



