No. 1.] ORIGIN OF HUMAN MONSTERS. 105 
mass, which barely outlines the embryo. Such a condition 
is found in No. 196. The tissues are nearly homogeneous, 
only the central nervous system and some of the large blood- 
vessels being recognizable on account of the increased number 
of nuclei in these regions. 
In No. 115 the amnion is greatly distended and the embryo 
is spread out upon it, much as is the case in the chick in 
normal development. The body cavities communicate freely 
with the ccelom, Wolffian bodies are still visible, and the 
central nervous system, heart and some large blood-vessels 
are represented as bands of round cells. 
Various degrees of dissociation of the organs are seen in 
different embryos, as is naturally to be expected. In No. 
292a, for instance, the outline of the body cavity is very 
marked, it being distended and partly filled with round cells. 
The amnion is also greatly distended, filling the entire ccelom. 
There is no umbilical cord. Some of the spinal cord is still 
sharply outlined; otherwise the dissociation is complete. 
In embryo No. 252 the dissociation is complete with the 
exception of the eyes, which have been converted into small 
black spots composed of pigment cells. The skin is also 
markedly thickened, the epidermis forming papillomata, as 
well as small lens-like bodies. 
In the specimens just considered only those organs which 
are present in the early part of the third week were seen, 
there being no signs of cartilage, muscles nor peripheral 
nerves. In the next group of ten specimens we have clearly 
the remains of organs and forms of embryos to correspond 
with normal ones of the latter part of the third week, that is, 
embryos 4 and 4.5 mm. long. 
This group can also be arranged in the order of the degree 
of pathological change. In No. 189 the central nervous sys- 
tem is open below throughout its whole extent. A number 
of motor nerve roots are developed, more in the region of 
the tail than elsewhere. There are no cranial nerves present. 
The heart is almost detached from the body, and the large 
blood-vessels are irregular in shape and changed entirely from 
