THE 



MONTHLY MICROSCOPICAL JOURNAL. 



FEBEUAKY 1, 1874. 



I. — On the Origin and Developnent of the Coloured 

 Blood Corpuscles in Man. 



By Dr. H. D. Schmidt, New Orleans. 



(Read before the TIoyal Microscopical Society, Jan. 7, 1874.) 



Plates XLIX., L., and lower part of LI. 



In the course of the last four years, I directed my attention, in 

 connection with a series of investigations into the histology of the 

 nervous tissues, also to their development. In order to gain as 

 much information as possible from the material which I made use of, 

 consisting of a considerable number of human embryos of all stages 

 of development, I concluded, at the same time, to pay some attention 

 to the development of the coloured blood corpuscles, and also to that 

 of the smaller blood-vessels. The investigations, relating to the 



EXPLANATION OF PLATES XLIX , L., and lower part of LI. 



[The Figures are correct, but the artist Las unhappily not placed them in 

 serial order on the Plates.] 



Fig. 1. — Small human ovum; natural size. The specimen, having been laid 

 open by several incisions, and emptied of its liquid contents, is here represented 

 as it appeared under water. Being flattened by its own weight, its diameter has 

 become considerably greater than it was previous to its being opened. 



Fig. 2. — Various forms of coloured motlier-blood corpuscles, which escaped 

 from the canals of the umbilical vesicle, showing the embryo-corpuscles in their 

 substance, as well as the concave dej^ressions on their surface. As they are 

 represented such as they appear, as illuminated with oblique light by means of 

 the achromatic prism of Abmham, the embryo-corpuscles, owing to the trans- 

 parency of the mother-corpuscle, seem to project from the surface of the latter, 

 which, however, is in reality not the case. Magnified 465 diam. 



Fig. 8. — View of the interior of a primary follicle of tlie umbilical vesicle, 

 still containing a considerable number of young coloiu'ed blood corpuscles in 

 diflereut stages of their growth, as well as a number of mother-blood corpuscles. 

 A number of blood corpuscles are seen to pass from the follicle into a canal, 

 situated between it and a neighbouring follicle ; a portion of the latter is seen 

 at the margin of the drawing. At the borders of the follicles, the delicate fibrous 

 tissue surrounding tliem is brought into focus, together with the faint outlines 

 of the hexagonal cells of the upper layer. For the sake of illustration, the latter 

 as well as tbe fibrous tissue are represented a little more distinct than they 

 really appeared when the lower layer of cells and the blood corpuscles were in 

 focus. Within the cells, the large nuclei as well as the small pale ones may be 

 observed. The whole object is represented as illuminated with oblique light. 

 Magnified 279 diam. 



Fig. 4.— Small portion of the wall of the umbilical vesicle, situated between 

 VOL. XI. E 



