226 JOHNSTON. [VoL. I. 



described above. From the central end of the cell arises a 

 slender, uniform, slightly varicose axis cylinder which runs 

 either centrally or backward -- that is, in the direction of all 

 other axis cylinders. I have also found in some cases several 

 short, slender dendrites arising from the central end of the cell 

 about the base of the axis cylinder. 



(4) Cells of Cajal. I have found at all levels of the granular 

 zone very conspicuous elements (Fig. i, //), measuring 8 to 

 20 by 24 to 40 /j,, which in my earlier preparations seemed 

 to correspond closely with certain cells with numerous axis 

 cylinders described by S. Ramon y Cajal (-91) in the cortex 

 of the rabbit, and afterward named by Retzius ('93) cells 

 of Cajal. Later preparations brought to view in many of 

 these cells characteristic end-branchings of some of the 

 processes in olfactory glomeruli, and a single distinct axis 

 cylinder arising from the cell body or from one of the 

 thick processes and running centrally and backward toward 

 the fore-brain. These cells, therefore, like all others of the 

 olfactory lobe except those with short axis cylinders, receive 

 impulses from olfactory fibers and transmit those impulses to 

 the fore-brain. It seems probable, however, that some of the 

 dendrites do not end in glomeruli, and that such dendrites may 

 receive impulses from many collaterals and so serve as impor- 

 tant parts of the collateral paths. Since coming to the above 

 conclusions there has come to my notice the recent paper of 

 Veratti ('97) criticising Cajal's interpretation of the cells in the 

 rabbit's cortex and announcing that each cell has a single true 

 axis cylinder. My account agrees with that of Veratti, and I 

 have therefore called the cells here described cells of Cajal. 



In addition to the elements described above, I have found in 

 a very few cases fibers ending freely in the glomerular zone 

 (Fig. i, c.f.) which probably correspond to the centripetal 

 fibers of Golgi ('75) and S. Ramon y Cajal ('90). 



The olfactory glomeruli do not differ in general appearance 

 from those described by S. Ramon y Cajal, Van Gehuchten 

 and Martin, Koelliker, Retzius, Loewenthal, P. Ramon y Cajal, 

 and others in mammals, birds, reptiles, and amphibia. In Aci- 

 penser the glomeruli vary in diameter from 16 to 240 //., and 



