123 



in ths bulbus, th3 olfactory neurones of the first order are 

 chninei to those of the second orier through the asuil tanf^^les 

 kno/<n as the olfactory glomer'ill; and that the neurones of the 

 second orier, mitral cells, send their axones through the trac- 

 tus to terninal stations described further on. Other neurones 

 of the olfactory lobe, having a purely accessory value, need 

 not detain us at present. 



S. The S tria tUTi. 

 The striatuTi is primarily a part of the olfactory appara- 

 tus, and its morphology must be interpreted with this fact in 

 mind. T'^o groups of neurones have become defined from the 

 general mass of the striatum for the especial reception of ol- 

 factory impressions. One of these lies next to the lateral 

 ventricle, the epistriatiim; while the other one is peripheral 

 in its location, the nucleus postolfactorius. The structure of 

 the principal mass, or general striatum, will be considered 

 after that of the epistriatum. 



a. Eoistriatu-n. — The epistriatum is a group of neurones 

 lying ventral and lateral to the lateral ventricle ( ^15.31, estr. ) 

 It comprises something like the inner fiftn of the entire thick- 

 ness of the striatum. While not so sharply ielimitei from the 

 outer levels as ^dinger ('96) has described for the reptilian 

 brain, the epistriatum of Mustelus is readily distinguished 



