AUTHOR’S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, FEBRUARY 28 
NERVE AND PLASMODESMA 
H. V. NEAL 
Tufts College, Massachusetts 
FIVE FIGURES 
That neuraxones develop as processes of ganglion cells scarcely 
admits of reasonable doubt in the light of the evidence now in 
our possession. Few today would challenge the truth of Har- 
rison’s (’13) assertion that ‘‘the work on the cultivation of tissues 
may be said without reserve to have completely proved the 
correctness of the conception of His and Ramon y Cajal.” The 
long controversy between the adherents of the cell-process theory 
and the supporters of the cell-chain hypothesis of neurogenesis 
has been finally settled in favor of the former. To say this, 
however, is by no means to assert that all problems of neuro- 
genesis have been solved. Such has never been the claim of 
Harrison or any other supporter of the Bidder-Kupffer hy- 
pothesis. There yet remain unsolved a number of controverted 
questions of great interest, some physiological and some morpho- 
logical, which neither tissue cultures in vitro nor observations 
upon sectioned material have been able to solve. Familiar 
examples of such are the problems of the genesis of the nerve 
sheaths and of the sympathetic cells. Further questions are 
suggested by the phenomena of nerve regeneration (Boeke, ’16). 
One of the disputed points in the histogenesis of nerve is 
whether or not there exists previous to nervous (neurofibrillar) 
connection between neural tube and myotome a connection by 
means of undifferentiated protoplasmic threads, or plasmodes- 
mata, or ‘fasernetz’ of Szily (04). Among those who assume 
the existence of such plasmodesmata it is a matter of dispute 
whether the plasmodesmata are primary—the result of incom- 
plete cell division, as first stated by Hensen (’64)—or secondary 
the result of protoplasmic outflow of medullary cells as first 
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