NATURE OF SENSE ORGANS 



29 



olfactory cell with the olfactory nerve-fiber was first seen 

 by Babuchin in 1872 who showed that in a gold-chloride 

 preparation, fibers could be traced from the nerve to the 

 cells that were suspected by Schultze to be sense cells. 

 In 1886 this connection was demonstrated with much 

 greater certainty in methylen-blue preparations by 

 Ehrlich whose results were con- 

 firmed the following year 

 by Arnstein. 



Because of the transitoriness 

 of methylen-blue preparations, 

 the results of Ehrlich and of 

 Arnstein were looked on with 

 some suspicion till they were 

 reproduced in Golgi preparations 

 by a number of workers, such as 

 Grassi and Castronovo (1889) 

 on the dog, Ramon y Cajal (1890) 

 on mammal embryos, Van 

 Gehuchten (1890) on rabbits, von 

 Brunn (1892) on man, Eetzius 

 (1892a, 1892b, 1894) on fishes, 

 amphibians, reptiles, and mam- 

 mals, and by many other later 

 workers on various vertebrates. 

 (Fig. 6) . The results of all recent 

 students in this field of histology 

 support the statement that the 



olfactory epithelium of vertebrates is composed of at 

 least three classes of cells : basal cells, ordinary epithelial 

 or substentacular cells, and sense cells from which the 

 olfactory fibers take their origin. Thus the opinion of 



Fig. 5. — Olfactory epith- 

 elium from a pig embryo 

 6H inches long; b, basal 

 cell; 0, olfactory cell; e, sus- 

 tentacular cell. After 

 Alcock, 1910, Fig. 10. 



