HUMAN MAGMA RETICULE IN NORMAL AND PATHOLOGICAL DEVELOPMENT. 15 



After the embryo had been carefully removed, the ovum was cut into blocks 

 which included its implantation. A block 1 mm. thick, which included the largest 

 circumference of the embryo, was embedded in celloidin, the sections being stained 

 in various ways. A photograph of this block is represented in plate 1, figure 4, 

 which shows strikingly the extent of the magma. Sections which have been stained 

 in hematoxylin and aurantia show the magma much as it appears in the other 

 embryos that have just been considered. There is a denser magma just under the 

 chorionic wall, and heavy strands radiate in every direction, with a fine network 

 resembling spider-web, among the main strands. A number of loose nuclei accom- 

 pany these strands, but they do not have the appearance of the nuclei of the main 

 wall of the chorion. They are mostly round and are of unequal thickness, simulating 

 very much the blood-cells. Occasionally there is a large nucleus. Sections which 

 have been treated by the Weigert fibrin method do not show these fibrils. This 

 confirms a previous experience which I have published elsewhere in my paper on 

 monsters, namely, that magma fibrils do not give the reaction of fibrin, nor do these 

 fibrils stain well in Van Gieson's mixture; however, they take on color similar to the 

 mesenchyme of the chorion. 



At points it appears as though these fibrils arise directly from the chorionic 

 wall. They stain intensely blue by the Mallory method, and in sections treated in 

 this way the nuclei of the mesenchyme of the villi look much like the accompanying 

 nuclei of the magma fibrils. On one side of the ovum a denser mass of the magma is 

 directly continuous with the mesenchyme of the chorionic wall. However, just in 

 this region the magma contains no nuclei. It, therefore, appears that the magma 

 fibrils must be associated, at least partly, with the nuclei of the chorionic wall. 

 Exceedingly good histological pictures were obtained from sections stained by 

 Heidenhain's method, which show all the transition stages between magma con- 

 taining no nuclei and magma very rich in nuclei. It would seem that there is quite 

 a free wandering of the nuclei along the magma fibrils, and whenever they come in 

 contact with the chorionic wall the fibrils enter it, showing direct continuity. The 

 most instructive specimens are obtained by the Weigert elastic-tissue stain, which 

 gives a slight blue-black tinge to the mesenchyme fibrils of the chorionic wall, as 

 well as to those of the centers of some of the villi. The magma itself takes on a very 

 light stain, but where it is in contact with the chorionic wall it grades over into its 

 blue network. It appears, then, that the centers of the villi, which represent their 

 older portion, stain somewhat with elastic-tissue stain; and, if we view the chorionic 

 wall as the more differentiated portion of the chorion, we must conclude that the 

 older mesenchyme fibrils behave more like elastic-tissue fibrils than do the younger. 

 At any rate, the magma fibrils do not take on elastic-tissue stain. 



From all that has been said it is clear that the mesenchyme of the chorionic wall 

 and the magma fibrils are continuous and, as I have pointed out elsewhere, they 

 together form a common syncytium. I have already demonstrated that very young 

 connective tissue arises directly from the mesenchyme, the earlier stages of which 

 I have designated as the connective-tissue syncj'tium. Towards digestive reagents 

 the connective-tissue syncytium gives somewhat the reaction of yellow elastic tissue, 

 just as do the mesenchyme and the magma of No. 836 when treated with Weigert's 



