Xne Ohio Journal of Science 



Vol. XX JUNE, 1920 No. 8 



THE ORIGIN OF CEREBRAL GANGLIA.* 



F. L. Landacre. 



The problem of the origin of the cerebral ganglia presents 

 many difficult, as well as many interesting phases. An attempt 

 to form some conception of the present status of the problem 

 by an examination of text books and monographs leaves one 

 suspended between the explanations that are so simple that 

 they will apply to no particular case, and observations and 

 descriptions that are so complicated that one can form no gen- 

 eral conclusion from them. 



Possibly it is too early yet to form broad generalizations 

 on this subject, and it is further possible that the generaliza- 

 tions may not seem what they claim to be on account of the 

 number of exceptions cited, but since we cannot avoid generaliza- 

 tion, and since even an incomplete generalization, provided 

 it directs our efforts, has its value, I have ventured to attempt 

 to reduce our present knowledge of this question to some 

 simple statements or formula which will, at least, clear the way 

 for investigation. 



The problem has its historical background, of course, but 

 much of this we must ignore for the present, unless it bears 

 directly on the point of view which seems to be the most tenable 

 at the present time. There is probably no more confused or 

 hopeless mass of literature in Biology than that dealing with 

 the cerebral nerves, especially the earlier literature dealing with 

 their relation to the problem of the vertebrate head. Most of 

 this we shall ignore, because the origin of the cerebral ganglia 

 present a distinct problem, whose solution will undoubtedly 

 throw much light on the larger problem. The head problem 

 is so huge that it can not be reduced to a simple generalization 

 at present. 



*Presidential address given before the Ohio Academy of Science at its annual 

 meeting in 1918. 



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