The Central Nervous System of Aphorura 
WILLIAM A. HILTON 
A large number of Collembola of the genus A phorura, species 
lutea and montis, were preserved by various methods for a 
study of the central nervous system. The individuals used 
were of all sizes, from less than 1 mm. to 114 mm. in length. No 
particular differences were noticed between large and small 
specimens. In all, even the smallest, difficulty was encountered 
in preservation, because it was hard to wet them with a cold 
fixing fluid. The method which was most successfully employed 
was to place the living animals in warm Flemming’s fluid, or to 
fix in the fumes of osmie acid. A large number of specimens 
were sectioned in all planes, the thickness which seemed best 
was about 5 microns. 
The accounts of the nervous systems of Collembola are very 
meagre; this is also true of the larger group of Aptera or 
Thysanura. The work of Boettger ’10, on Lepisma has been 
very useful as a reference. Mention should also be made of the 
paper of Grassi ’89. In this last, three divisions of the brain or 
supraesophageal ganglion are given for the Thysanura, based 
on the study of Campodea, Japyx, Nicoletia, Lepismina, 
Machilis and Lepisma. His divisions are: (1) The forward 
one connected with the antennal nerve. (2) The second division 
connected with the eyes, when they are present. (3) A caudal 
division connected with visceral nerves. 
Among the recent work dealing in part with the nervous 
system of Collembola, we have the paper of Becker 1910, which 
is especially concerned with the interesting postantennal organs 
of this group of insects. The article of Philiptschenko 1912, 
although an account of the embryonic development of one of 
the Collembola, Jsotoma cinerea, has some consideration of the 
general nervous system of late stages. 
One of the most striking things which is noticed in the exam- 
ination of this little blind Aphorura, is the relatively large size 
