The Central Nervous System of Aphorura 



WILLIAM A. HILTON- 



A larg'e mimlier of Colleinliola of the genus Aphorura, species 

 lutc(t and jiioiitis, were iireserved by various metliods for a 

 study of the central nervous system. The individuals used 

 were of all sizes, from less than 1 nnn. to IV-i mm. in length. No 

 ])artif'ular differences were noticed lietween large and small 

 specimens. In all, even the smallest, difliculty 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 osmic acid. A large number of specimens 

 were sectioned in all i)lanes, the thickness which seemed besi 

 was about 5 microns. 



The accounts of the nervous s.vstems of C'ollembola 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 '8S). In this last, three divisions of the brain or 

 supraesoi)hageal ganglion are given for the Thysanura, based 

 on the stud.v of Campodea, Japyx, Nicoletia, Lepisin'uui, 

 MiuhiUs 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, Isotoma cincrea, 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 



