474 E. V. Cowdry, 



have now been studied from almost eveiy conceivable point of view. 

 The psj'Chiatrists have repeatedlj^ attempted to find in them an ex- 

 planation of obscure mental conditions, the phj^siologist has associated 

 them with the phenomena of fatigue, neurologists have studied their 

 development, sti-ucture and cytoplasmic arrangement, and the bio- 

 chemist has analysed them microchemically and determined their compo- 

 sition with a certain degree of precision. 



The neurofibrils have been brought into prominence chiefly through 

 the researches of Apathy, Cajal, Bethe and others. They, in turn, 

 were seized on by neurologists in expectation that they might serve 

 to elucitade the causation of mental diseases of doubtful character, 

 and afford some clue to the interpretation of the phenomena of the 

 conduction of the nervous impulse. Neither of these hopes has as yet 

 been realized. Neurologists are divided into two schools: those who 

 believe that the neurofibrils are the medium of the conduction of the 

 nervous impulse, and those who think that they are merely supportive 

 and play no part in it. The origin of these structures is in active 

 debate. 



The first descriptions of a canalicular system in nerve cells are 

 obscure and difficult to interpret. The stimulus for all the recent 

 work came from the researches of Golgi, who published his first 

 contribution on the internal reticular apparatus in 1898. Many in- 

 vestigators have subsequently described networks and canalicular 

 structures of diverse appearances in nerve cells, the identity of which 

 is at present under discussion. Little, if anything, is known of the 

 development or of the function of this reticular apparatus. 



Although mitochondria were observed and even figured in nerve 

 cells by Altmann as far back as 1894, they have not been recognized 

 as such and studied until very recently. They are only now being 

 brought into prominence as a result of the rapprochement which is 

 taking place among neurologists and histologists. Formerly the neuro- 

 logist was content to study nervous tissue onty, and the histologist 

 exclusively non-nervous structures. The discoveries made by the one 

 were rarely correlated with those made by the other. In the field 

 of neurological cytology alone, the terms given by each investigator 



