192 JOURNAL OF CoMPARATIVE NEUROLOGY. 
field have observed mitotic figures in the nerve cells, not all 
agree that they result in cell proliferation. SANARELLI (27) 
(1891) used a hot needle on the cerebrum and cerebellum of 
rabbits. Three days later he found karyokinesis in the nerve 
cells, where it had not progressed in a normal manner, nor pre- 
sented all the stages of true mitosis. At this time there 
appeared in the normal brain substance, elements resembling 
giant nuclei which he believes are the results of incomplete, 
atypical karyokinesis of the nerve cells. After eighty days the 
stab canal was filled with pure connective tissue, which was sur- 
rounded by a zone of neuroglia, and this in turn bordered on 
the normal brain substance. Nerve cells were not present in 
the connective tissue nor in the neuroglia formation. 
MarInEsco (22) (1894) using the method of Corn and 
SANARELLI on the brains of young rabbits, guinea-pigs and 
cats, observed in the ganglion cells karyokinetic changes which 
did not, however, reach the ‘‘meta”’ stage. The cicatrix which 
formed later contained neither nerve fibers nor nerve cells. 
TscHISTOWITSCH (32) (1898) found that brain wounds in young 
rabbits and dogs healed with pure connective tissue. 
It is plain that nerve cells may begin to proliferate, some- 
times not reaching the stage of metakinesis (MARINESCO), 
sometimes producing giant nuclei (SANARELLI), and at other 
times proceeding to cell division, with rapid disappearance of 
the new-formed cells (CoEN). It is doubtful whether these new 
cells ever continue to exist, although they are reported to do 
so by Tepescur. It will be seen that observations have been 
confined largely to the nerve cells, the fibers receiving little 
attention. 
Several investigations have been made upon scars from 
lesions in the human brain. WorcesTER (38) (1898) describes 
a case of complete degeneration of the right half of the cor- 
pora quadrigemina in a woman of 51 years. The region is 
filled with neuroglia. There are no nerve cells; but in the 
midst of the area is a much convoluted bundle of nerve fibers 
which appears to have grown in from the region of the red nu- 
cleus. ZIEGLER (39) (1876), KaLpEn (19) (1891), and CHEN- 
