448 
Dr Duckworth, Description of a 
view from the right side). Evidently the brain was profoundly 
affected. An enlarged view of the lateral aspect of the brain is 
shewn in Plate xvi, Fig. 5, and I have also photographed the 
encephalon of a normal specimen employed as a “ control.” The 
right side of the abnormal specimen is represented in Fig. 5 : 
in the normal example (Fig. 6) the left side is shewn. 
In the monstrous pig, the brain was symmetrical, but consisted 
only of medulla oblongata, pons varolii and cerebellum, with the 
structures immediately connected with these parts. Moreover the 
cerebellum, and (to a less extent) the pons and the bulb, were 
reduced in size ; the cerebellum fitted almost like a cap over the 
pons and bulb. The lateral parts were undeveloped and to this 
defect, the lack of mass of the cerebellum was chiefly due. The 
median part, or vermis, was therefore unduly prominent, but both 
this and the lateral portions were foliated. 
The foreging points are illustrated by Figs. 7 and 9 (Plate xvi), 
which represent the ventral (Fig. 7) and dorsal (Fig. 9) aspects 
respectively. Figs. 8 and 10 shew the normal conformation of 
these parts. 
The anterior aspect of the cerebellum was quite smooth. 
There was no suggestion whatever of any inflammatory process 
having been at work, and the tissues appeared perfectly normal in 
texture. 
Thus it seems as though the brain was represented only by 
derivatives of the third primitive cerebral vesicle, and every 
observation pointed to the conclusion that we are here dealing 
with a case in which the second and the first vesicles had never 
been formed, not with an example in which after a brief course of 
growth these vesicles had retrogressed and degenerated. Evi- 
dently the arrest took place at the isthmus, a morphological 
frontier-line between the second and third cerebral vesicles. It 
is of importance to note that (as shewn in Fig. 3) the third 
cerebral flexure had occurred and was distinct. 
The abnormal brain (including the bulb) was cut off from the 
spinal cord. After imbedding it in celloidin, I prepared a number 
of longitudinal sections of the whole brain, believing that it would 
be of interest to trace the central canal forwards as far as possible. 
The appearance of a longitudinal section is shewn in Fig. 11 
(a tracing made with Edinger’s projection apparatus, from one of 
the mounted specimens). The floor of the central canal is repre- 
sented by the upper border of the bulb, and it terminated as a 
distinct pit or depression (os) in the floor of the “ fourth ” ventricle 
(here the only ventricle). Anteriorly to this pit, the mass of the 
bulb will be seen in the drawing to run uninterruptedly upwards 
into the central portion of the cerebellum. In Fig. 12, I have 
reproduced a tracing from a section of the corresponding region 
