HUMAN MAGMA RETICULE IN NORMAL AND PATHOLOGICAL DEVELOPMENT. 1 1 



tion of the magma in an earlier stage. In this specimen the chorionic cavity is filled 

 with a dense mass of fibrils, throughout which are scattered numerous nuclei, as 

 shown in their plates 3 and 4. The specimen was not i^erfectly hardened and there 

 is a small cleft between the chorionic wall and the mass of magma. As yet there 

 is no exoctt'lom, showing that it is younger than the Peters specimen. 



More advanced stages of the condition of the magma are represented in the 

 specimens described by Jung and by Strahl and Beneke. In the Jung specimen the 

 cavity of the ovum is filled with a very pronounced magma, running together in 

 stronger bands, as in our own normal specimen, No. 836, to be described later. The 

 larger cavity Jung marks "exocoelom," but it is not clear that this is lined with 

 endothelium. From his large illustration one gains the impression that the speci- 

 men is somewhat pathological, for it is of the same type as numerous specimens in 

 our collection w^ith embryos that are usually found to be pathological. Taking the 

 illustrations given in Jung's plates 1 and 2, the specimen again appears to be patho- 

 logical, and I should be inclined to pronounce it such did not his plate 6, figure 17, 

 show this same section on an enlarged scale, which gives a very sharp outline of dif- 

 ferent embryo structures and scattered through them are numerous cells undergoing 

 division. It would be impossible, with our present knowledge, to accept such sec- 

 tions as coming from a pathological embryo. The specimen described by Strahl and 

 Beneke is of about the same stage as the Jung specimen, although the magma does 

 not seem to be so well pronounced. It is unequal in mass and has scattered through 

 it delicate strands, as shown in their figure 63. In fact, the above-described specimen 

 underlies also the diagram on the form of the coelom given bj^ Strahl and Beneke 

 on page 18 of their monograph. 



Magma of uniform consistency, as seen in the Brjxe and Teacher specimen, 

 soon arranges itself in bands, which gradually become more and more pronounced 

 in older specimens. Between these bands are sjjaces filled with fluid, and those 

 spaces near the embryo become hned with endothelium to form the exocoelom. 

 There are other spaces between the exocoelom and the chorionic wall. The sharper 

 bands of magma fibrils — well shown in our embryo No. 836 (plate 1, figs. 3 and 4) — 

 apparently support the embryo and the wall of the exocoelom within the chorion. 



We have in our collection an excellent embryo. No. 391, which is a little larger 

 than that described by Strahl and Beneke. This specimen came to us in formalin 

 and was opened with great care. It was found that the embryo and appendages 

 were suspended by means of numerous delicate fil)rils which radiated from them to 

 the chorionic wall. As the sections were stained with cochineal, the fibrils do not 

 show in them, so that this description is based entirely upon the apearance of the 

 uncut specimen. In general the specimen appears to be normal. 



Our specimen No. 779, somewhat older than the one just mentioned, appar- 

 ently contains no magma. It also was hardened in formalin. The ovum is entirely 

 covered with villi, which branch twice, are of uniform size, and appear to be normal. 

 In the main chorionic wall there is a pronounced fold. The specimen was bent 

 along the line of the fold, but the chorion was gradually dissected away with the 

 aid of direct sunlight. The chorion is entirely lined by a smooth membrane, and 

 contains a cavity which is filled with a clear fluid and which apparently contains 



