Proceedings of the Association of American Anatomists XTII 



The most important result was the discovery of abundant glycogen 

 in the nerve cells of the nu'cl (spinal cord) of Amphioxus and Asymme- 

 tron. and also in the l)rain of Ammocretes. All previous ol)servers have 

 stated that glycogen is aljsent from the nervous system of vertebrates. 



KARYOKINETIC DIVISION IN THE SPINAL GANGLION CELLS OF 

 TRITON LARV.T]. By Ross G. Harrison. The Anatomical Labora- 

 tory, Johns Hopkins University. 



In Triton larvte (10-13.5 mm. in length) spinal ganglion cells with 

 long and defined process were found undergoing karyokinetic division. 



■ON THE HISTOGENESIS OF SPINAL GANGLIA IN MAMMALS. By 

 George L. Streeter. Department of Anatomy, Johns Hopkins Uni- 

 versity. 



Spinal ganglia of the chick, pig and man were studied by comparing 

 teased preparations with preserved material cut in paraffin. The ob- 

 servations are as follows : 



1. The cells of the neural crest, as they separate ofi: and migrate ven- 

 iralward between the myotome and neural tube, possess elongated vacuo- 

 lated cell bodies and appear in well preserved material to fuse into cell 

 clumps, possibly a sjaicytium. At this time ganglion cells cannot be 

 ■distinguished from capsule and sheath cells. 



2. Xeural crest cells are difi'erentiated into — 



a. Ganglion cells. — Formation of processes. Condensation of pro- 

 toplasm of cell body. Appearance of basic stainable substance on 

 periphery. Increase and clumping of stainable sul)stance (Xissl 

 bodies). Xucleus eccentric and comparatively late it retires to cen- 

 ter of cell and assumes resting appearance. 



b. Capsule cells. — Cell body converted into branching flat irregu- 

 lar processes which envelop early the ganglion cells and resemble 

 neuroglia cells. Capsule cells are identical with sheath cells. 



3. The early ganglion cells have a fusiform shape with processes at 

 the poles. Between these are -found cells which develop later as a 

 secondary growth and are characterized by greater irregularity in shape 

 of cell body, and in situation, size, and number of processes. 



4. Many bipolar cells in pig and man do not undergo a transformation 

 into the Eanvier T cells. Some unipolar cells seem to be unipolar from 

 the first, 



5. Multipolar ganglion cells are found in considerable variety in adult 

 liuman spinal ganglia. 



L^' 



