NERVUS TERMINALIS: TURTLE 441 



variation above the average size which the smallest cells, which 

 had nuclear diameters of 5.3 ju, showed below the average size. 

 Three cells of this smallest size were found to be included among 

 the eighty measured. 



Reference to the table will indicate that the cells of the gas- 

 serian, spinal, and cihary ganglia have an average nuclear diam- 

 eter of 8.3 n or more, even when the smaller cells, which in the 

 spinal and cihary ganglia may with some show of reason be con- 

 sidered as a separate group, are included with the larger in 

 computing the average. If the two types are considered sepa- 

 rately, the average size of the larger cells, which may be considered 

 as the typical cells in the three ganglia under consideration, is 

 considerably increased, being 9 m for the ciliary ganglion and 9.8 

 IJL for the spinal and gasserian ganglia. The sympathetic chain 

 ganglia, the small cells of the ciliary, and the sphenopalatine 

 ganglion cells, together with those of the nervus terminahs, 

 have an average nuclear diameter of approximately 6.7 m or 

 less. 



WTien these facts are considered in connection with the dif- 

 ference in form of the cells of the terminahs clusters, and their 

 manner of distribution in more or less irregular clusters instead 

 of in the compact ganglia of the sensory nerves, it seems reason- 

 able to conclude that the majority of cells at least, which are 

 found in the ganghonic clusters of the nervus terminahs in the 

 turtle, are related to the sympathetic nervous system. 



The writer 's previous work on various mammals, together with 

 Huber and Guild's ('13) comparison of terminahs cells with 

 those of the gasserian ganglion in the rabbit, points in the same 

 dhection for mammals, as does the work of McKibben ('14) on 

 the terminahs ganglion of Mustelus, for the selachians, and 

 certain of Brookover's observations in ganoids for that group of 

 vertebrates. 



At this point attention may also be called to the position of 

 some of the ganglion cells at the point of entrance of the nerve 

 roots into the brain, as illustrated in figure 2. The position of 

 these cells is interesting. As shown in the figure, some of them 

 appear to be migrating outward from the brain wall. Both cells 

 and nuclei are elongated, and the cells lie just at the border of 



