116 MALL. [VoL. XIX. 
The remaining nine embryos of the fifth week may be con- 
sidered together, for in many respects they are alike. In all 
of them the bodies of the vertebrz are well outlined and the 
precartilages of some of the ribs are laid down. They may 
be compared with the normal embryos, Nos. 109 and 163, 
whose skeletons have been studied with great care by Bar- 
deen. It may be that the first four embryos of this group 
belong to the fourth week, for it is certain that their develop- 
ment is not as far advanced as No. 163, but they are fully as 
large. The slight difference may be due to errors in measure- 
ments or to the possibility that pathological embryos of 
younger stages may simply “swell” but not develop. How- 
ever, the opposite is usually observed. 
Specimens Nos. 54, 133, 348, 288a, 343 and 177 show mucn 
the same changes in them. The tissues are well dissociated, 
with a variety of other changes in the body. In Nos. 54 and 
343 the front end of the brain is missing and the ventricle 
communicates with the exterior of the body, as if the neuro- 
pore were open. In these two specimens, in which the cere- 
bral vesicles have been fully destroyed, there are but few 
pathological changes in the rest of the body. They may be 
compared with No. 256 (Fig. 8, Plate III), in which the 
fore-brain was removed by mechanical means, that is, through 
rough handling, and is in every respect an anencephalic mon- 
SEE. 
No. 133 is well dissociated, but in it, as in the rest of this 
group, the liver is more like the normal, showing that in 
later stages the liver is more resistant than it is in younger 
ones. No. 348 shows about the same changes, only that in 
addition the embryo as a whole is disintegrating. The de- 
formed embryo from specimen No. 288a is from a mole in 
which the chorion was found to be collapsed. The position of 
the embryo is in the upper right hand corner. In No. 177 the 
process of dissociation has outlined the ribs into two zones, 
an outer and an inner, although no true cartilage is present. 
Back of the eyes, in the occipital region, there are two car- 
tilaginous masses, much too well developed for an embryo 
