122 MALL, [VoLt. XIX. 
Embryos 14 mm. long repeat the story given by those 
13 mm. long. The least amount of change is found in No, 
270, which is nearly identical with No. 311. However, the 
brain is not quite so solid, the dissociation of the tissues of 
the body is about of the same degree and the frontal process is 
united to the thorax below. Within the medulla there are 
papilliform sprouts of nerve tissue which extend into the 
ventricle, just as in No. 311. No. 346 may be a little older 
than No. 270, but the changes in it are not quite so advanced, 
nor has the frontal process united with the thorax below. The 
head and neck are also straight in Nos. 262 and 232, the 
changes in the tissues being very advanced. In No. 262 the 
cerebral hemispheres form a solid mass, which looks like an 
abscess, the medulla is much distended and its thin anterior 
wall protrudes through the mouth. Much the same condition 
is found in the cylindrical head of No. 232. In it the large 
fifth nerve may be seen running to the surface of the body, 
and acts as an index to tell how much of the head has become 
atrophied. The arms and legs are gorged with well stained 
round cells, indicating that secondary changes have taken 
place in them. 
The marked changes which have taken place in the brain 
and head have met their end in embryo No. 276. Here we 
find advanced changes in the head, but the body is much like 
the other specimens. The medulla is greatly distended and 
fills entirely the rounded top of the body, the rest of the brain 
having been expelled through an opening which is still pres- 
ent. Around the edge of it the epidermis is piled upon itself, 
apparently attempting to heal the wound. The severe changes 
in the chorion and the long duration of the process have ended 
by destroying entirely the brain and the top of the head, 
leaving the body of the embryo capped only with a remnant 
of a head containing a dissociated medulla. 
Most radical changes are found in specimen No. 365. The 
embryo is within a fibrous chorion. There is spina bifida, 
iniencephaly and anencephaly. The mouth is closed completely 
by the tongue becoming adherent on all sides. The tissues of 
