Hatai, Ganglion Cells in the Rat. ill 



As the above table shows, the cervical spinal ganglion con- 

 tains the greatest number of the cells ; the lumbar comes next, 

 while the thoracic contains the smallest number. The most 

 interesting as well as most important point shown by Table I is 

 the approximate constancy of the total number of the ganglion 

 cells during the period chosen. The excess of the number of 

 the cells in the rat of 167 grams over that of 10.3 grams is 

 10% in cervical and 13^ in lumbar, while in the thoracic it is 

 3.5%. The question at once arises whether this excess means 

 the increase of the number of the cell-bodies with age or 

 whether it is due to individual variation merely. The only argu- 

 ment in favor of interpreting these figures as showing an in- 

 crease of the number of cells with age is the fact that in the 

 68.5 and 167 gram rats, the number of cells is greater than in 

 the 10.3 and 24. 5 gram rats. Against the idea of the increase 

 is the fact that the 24. 5 gram rat shows fewer cells than the 

 10.3 gram rat, and that in the thoracic and lumbar ganglia the 

 167 gram rat shows fewer cells than the 69 gram rat. More- 

 over, there is no indication of cell division in these ganglia. 

 We therefore consider the differences here observed as due to 

 individual variations. The total number of cells is however the 

 sum of two sorts : the small and the large. 



BuHLER ('98) made the following suggestions concerning 

 the small cells: "Es kommt, wie ich mich bei Frosch und 

 Krote und auch beim Kaninchen iiberzeugen konnte, physiol- 

 ogischer Weise zum Untergang speciell der grossen Spinalgan- 

 glienzellen. Die Degeneration verlauft in verschiendenen 

 Formen und allem Anschein nach wenig rapid. Man siet in 

 einem Spinalganglien des Frosches ca. 20-25 untergehende 

 Zellen, beim Kaninchen relativ noch viel weniger. Die verloren 

 gegangenen Zellen miissen ersetzt Werden, und dies geschiet 

 Wahrscheinlich dadurch, das eine der kleinen durch Wachsturo 

 ihre Stelle einnimmt. Da nach dem friihesten Jungenstadium 

 eine Vermehrung von Nervenzellen nicht mehr Vorkommt, 

 muss das Spinalganglien, um fiir die Zeit des Lebens functions- 

 fahig bleiben zu konnen, in der Anlage geniigendes Ersatz- 

 material in Gestalt von Reservezellen mitbekommen. Genauere 



