CRANIAL SYMPATHETIC GANGLIA IN THE EAT 171 



until the entire developmental history of the cranial sympathetic 

 ganglia of lower forms has been made a subject for reinvesti- 

 gation will we be enabled to make any sort of generalization 

 or homology. 



MATERIAL AND METHODS 



The present study is concerned entirely with the development 

 of the cranial sympathetic ganglia in the mammals. The ma- 

 terial used consisted largely of rat embryos. Both albino rats 

 and gray rats were employed, the two series serving to supple- 

 ment one another. The material available from the depart- 

 mental collection at the beginning of the work consisted in fifteen 

 series, covering a fairly large range. During the study forty-four 

 series were added to the collection. The latter embryos were 

 obtained from The Wistar Institute of Anatomy and were pre- 

 pared by the writer with methods especially suited to the type 

 of study demanded. Litters ranging in age from ten and one- 

 half to seventeen days were employed, material being removed 

 at approximately half-day intervals. For general purposes, 

 embryos were fixed in Carnoy's 6-3-1, Zenker's fluid, and Bouin's 

 fluid. In addition silver impregnations were obtained by the 

 Ranson pyridine-silver technique (Ranson, '12). Vom Rath's 

 picro-acetic-osmic-platinic chloride technique, following the pro- 

 cedure of Neal ('14), was used with excellent results in some 

 stages. Where staining was necessary, hematoxylin and orange 

 G. or eosin were generally employed, once Held's erythrosin- 

 methylene blue. Several impregnations of heads of young rats 

 ranging in age from twelve hours to fourteen days were obtained, 

 using the Huber-Guild technique as modified by Larsell ('18). 

 In two cases the glossopharyngeal nerve was dissected out into 

 the tongue and the region removed and stained by the Nissl 

 technique. In order to have some check on the observations 

 of Kuntz ('13), seven pig embryos were examined for the early 

 stages in the formation of the sphenopalatine and otic ganglia. 

 The writer wishes at this point to express his gratitude to Prof. 

 B. F. Kingsbury for originally suggesting the study and for 

 assistance during its progress. Additional expenses incurred 



