THE FISSURA HIPPOCAMPI TO 
to find them in the sheep, ox, and pig. ‘The maceration arte- 
facts are so great in Marchand’s embryos (’91, p. 312) that his 
description of the hintere Bogenfurche is of little value. But in 
treating of the vordere Bogenfurche (45-mm. embryo, figs. 1 and 
2) he says that the olfactory ‘‘bulb is separated from the sub- 
stantia perforata by a transverse sulcus, which is continued on to 
the medial surface as the ‘vordere Bogenfurche’ (incisura prima).”’ 
In 1909, although he had recognized the radial folds as arte- 
facts, Marchand nevertheless described a slight indentation (in 
the fourth month) which extended from the tip of the temporal 
pole to the region just anterior to the lamina terminalis. 
The following year Cunningham (’92) defined the fissures in 
question as “‘a series of furrows which radiate in a stellate manner 
from the fissura arcuata (Bogenfurche) toward the free border 
of the hemisphere.’”’ He believed that ‘‘the influence at work 
in calling the infolding of the cerebral wall into existence appears 
to be a purely mechanical one, viz., a restraint placed upon the 
longitudinal growth of the hemisphere; and this being the case it 
is easy to understand how the number and depth of the fissures 
will vary with the degree and kind of restraint which is applied” 
(p. 14). As to their obliteration, he thought that as the cerebral 
vesicle thickens and the hemisphere elongates, the stellate fissures 
become detached one by one from the previous arcuata. ‘‘In 
all cases, however, the posterior hippocampal portion is preserved 
in situ’ (p. 16). The anterior part is obliterated at the time of 
the disappearance of the radial folds. He suggested, as did 
Anton (’86), that the disappearance of the transitory fissures has 
some connection with the appearance of the corpus callosum. 
He cites several cases of radial fissuration in the brains of Macro- 
pus and Halamaturus in which the corpus callosum is rudi- 
mentary, and a few instances of congenital absence of the corpus 
callosum in man. In these brains the radial appearance of 
fissuration is evident. 
In 1898 Hochstetter reported that he could produce the fissura- 
tion under discussion by waiting several hours after the death 
of young fetuses before fixing them. Six years later he challenged 
His to meet him in Jena. But His could not come. Hochstetter 
