1894.] Entomology. 1059 
dorsal aspect. As soon as the opening closes, however, the young 
larva is truly a young larva, possessing no organic connection with 
the other egg structures. The first use it makes of its liberty is to 
bend the tail forwards and, as it were, creep up its own ventral sur- 
face, assuming in this process an S or pot-hook shape, until at length 
its position is reversed, the dorsum being now along the cireumference 
of the egg and the venter being central. The head aud tail sometimes 
merely meet in the (flattest eggs), sometimes slightly overlap, whilst, 
in the dome-shaped eggs the head so overlaps as to take very often a 
central position in the vertex of the egg, forming a dark spot there, as 
in Acronycta, Skippers, and many others. 
* The essential importance of this observation is, that it shows that 
the embryonic position of the nervous system is the same in insects as 
in vertebrates, and since it must, therefore, be identified also in the 
mature animal, it follows that the venter of insects corresponds ana- 
tomically with the dorsum of vertebrates, and vice versa. 
“As regards the actual change of position itself, and the position 
afterwards taken by the larva, it seems to me that the important point 
is that the larva whilst still truly an embryo, that is, whilst still attached 
to the yelk and egg structures, has the venter outwards, and the dor- 
sum towards the center of the yelk or egg ; but when it becomes free 
it is no longer an embryo, it moves how it likes, and through the posi- 
tion it takes up seems to be very uniform throughout each species and 
and even throughout whole families ; still this has little, if any, embry- 
ological significance. I have frequently seen larve making this S 
movement, and though I have called it ‘creeping up its own ventral 
surface, it goes on slowly, without any apparent voluntary or even 
movements, and appears to be due to the mere force of the growth and 
development of the larva. Sometimes it seems as if the lengthening 
of the larva led to the extremity of the tail impinging against the side 
of the egg-shell and instead of sliding onwards, being caught and bent 
up. It is associated no doubt with the completion of the growth of the 
dorsal surface previously defective by the large umbilical opening, and 
now more abundant in proportion to the ventral surface. It proceeds 
slowly and steadily, so that usually some progress may be noted in five 
or ten minutes. 
* Very shortly after, what appear to be voluntary movements of 
swallowing take place, the remainder of the yelk disappears, and the 
remaining fluid is either absorbed by the larva through the skin, or 
evaporates through the shell; the traches become visible by getting 
filled with air, and the larva begins the process of eating through the 
shell." 70 
