The fiuer Anatomy of the Neivoiis System of Myxiiie glutinosa. 375 



three different tracts, which spring- intermingled from the Area olfac- 

 toria. One, the Tractus biilbo-epistriaticus, passes first along in a 

 caudal direction mixed with the other two, turns abruptly in right 

 angle laterally and enters a cell nucleus situated near the lateral 

 surface of the brain, the Epistriatum. The Nucleus becomes less 

 defined when approaching the ventral part and could perhaps be 

 considered homologous with the Striatum itself, or it is perhaps more 

 probable that the Striatum and Epistriatum are not differentiated 

 from each other in Myxiue. In higher animals there is found another 

 connecting tract, the Tractus bulbo-corticalis, but there are naturally 

 no traces of this to be found in Myxine, which is entirely devoid 

 of any cortex or pallium. 



The next nerve tract is the Tractus olfacto-habenularis, w4iich 

 connects the olfactory lobe with the Thalamencephalon. In the 

 beginning this runs in a similar direction to the previous one and 

 passes in straight line and in caudal direction to the Ganglia habe- 

 nulae, which it enters. Part of the same at least seems to decussate 

 in the Commissura habenularis and there is a drift of fibrils (which 

 may be seen in stained preparations) from this commissure towards 

 the cell nuclei of the Thalamus, from which cells they probably 

 spring. I have not been able to demonstrate this last fact with the , 

 method of GoLGi, but as similar arrangement has been found by 

 Mayer in Ammocoetes it is likely that the same arrangement exists 

 in Myxine. 



In sagittal sections stained with Haematoxylin according to 

 Wolters, I have found a nerve tract which leaves the Ganglia 

 habenulae, turning downwards and towards the lower part of the 

 olfactory lobes. This is probably only an inferior branch of the 

 Tractus olfacto-habenularis. The olfactory lobes are connected with 

 each other through a commissure (or nerve tract) that passes first 

 caudally to the Lamina terminalis, where it turns and passes in a 

 rostral direction to the other lobe, the nerve tract thus obtaining a 

 shape resembling a horseshoe. 



This tract is rather difficult to demonstrate with ordinary stains, 

 even Iron-haematoxylin not giving satisfactory results, but such are 

 obtained by the Haematoxylin method of Wolters and by the Golgi 

 process. Edinger (U) states that all parts of the brain that have any 

 connection wit the olfactory apparatus are in connection with the 

 corresponding parts on the other side of the brain through powerful 

 nerve tracts which all cross in one place in the median line, the 



