202 General Notes. [Feb. 
lobulated liver. The neural surface is outlined first, then the 
sides and hzmal wal 
The mesoderm is first differentiated when the entoderm sepa- 
rates from the ento-mesodermal layer, but for a long time it lingers 
in the germinal area. It then segments, and there is a preoral 
segment which contains a cavity like those of the post-oral series. 
The somatopleure is thicker than the splanchnopleure. Beyond 
their character separate, and become the primary blood-corpus- 
cles hey fill the space on the back of the embryo, which the 
authors afer as the homologue of the segmentation cavity. 
Later the mesodermal layers unite—first above and later below 
mesodermal origin, and even before the union of the layers of 
either side the histological differentiation of endothelium and 
muscular layers is eviden 
The first traces of oa nervous system appear as ectodermal 
thickenings. In each segment appear, on either side, two eleva- 
tions. Of these the lateral give rise to the appendages, ber 
median to the ganglia. At first these latter are simple 
dermal thickenings, but soon a rapid process of wall: pronieanoa 
takes place—first in the cephalic, then in the body region—in 
the following manner. In the head there are from fifteen to 
twenty places, in the other segments from ten to twelve, where 
this growth takes place. Each has the appearance of a groove, 
and in section these grooves are seen to be simple cavities which 
soon disappear by the growth of the bounding cells, In this 
way a very rapid proliferation is possible, but the authors do not 
consider the point whether it have any phylogenetic importance. 
The development of the brain is distinguished from that of the 
rest of the nervous system in that an accessory fold takes part in 
its formation. This fold was previously recognized by Metschni- 
in the scorpion and by Balfour in the spiders ; it is distinct 
from the grooves mentioned above. A groove is formed around 
the periphery of the procephalic lobes, which becomes deeper and 
finally forms a right and a left cerebral vesicle. Next a second 
_ fold arises and forms a pouch on either side, the mouths of which 
are directed laterally. These are the first traces of the median 
eral eyes are developed independently, but their 
history has not been worked out. 
The coxal glands, when first seen, appeared as a pair of tubes 
opening externally at the base of the second(?) pair of feet. 
Later the tubes were much coiled. Two portions could be dis- 
tinguished,—an inner, arising from the spla eure and com- 
. ASE S Me ratom by a broad funnel, ond a S 
DEE AA E Aa 
M 
mo EN a ne 
SRE ge EE a E a 
