400 MINOT. [VoL. II. 
pass on to direct observations. In the placental villi of embryos 
of four months and older, the mesoderm exists in two principal 
forms, —adenoid tissue and fibre-cell tissue around the blood- 
vessels. The adenoid tissue, Cut 21, is that of which the sup- 
posed development has just been sketched ; it may be considered 
as the proper tissue of the villus. It consists of a network of 
protoplasmic threads, which start from nucleated masses (cells). 
There are many large meshes, which are partly occupied by the 
coarsely granular wandering cells, /, 4, which are scattered about, 
and are usually present in large numbers. About the capilla- 
Cut 21.— Adenoid tissue of a villus from a placenta of four months. /,4,/ 
wandering cells; wv, v, capillary blood-vessels; a, finer meshwork from near a 
capillary. X 352 diams. 
ries the network is much more finely spun. Kastschenko, 107, 
454, found the wandering cells most abundant near the epithe- 
lium, but I have noticed no such peculiarity, except that they do 
not often enter the dense perivascular tissue; and as the blood- 
vessels are centrally situated, the adenoid tissue and the wander- 
ing cells in it are of course more peripheral. It seems to me 
that the leucocytes are distributed more or less evenly through- 
out the adenoid tissue. I fail to recognize any intercellular sub- 
stance. The abundance of nuclei deserves special mention. 
Around all the non-capillary vessels the mesoderm is very dif- 
ferent, for it exhibits distinct intercellular substance, with a ten- 
