374 John F. Holm 



fibres, we find the arraug-ement of the auatomical elements in the 

 olfactory bulb of Myxiue agree in the main points with that existing 

 in higher animals. Fig. 14 shows a section through the Formatio 

 bulbaris from a Golgi preparation. In the Stratum griseum behind 

 the Glomeruli we find impregnated cells which in their form resemble 

 the mitral cells described in higher animals. These are two some- 

 what diiferent kinds of cells, one kind of somewhat oval shape 

 {ol.c in the fig.) is situated quite close to the . Glomerulus, sending 

 one protoplasmatic process into the same, where it ends in a rich 

 arborisation which fills it up. The axis-cylinder springs from the 

 other pole and joins the olfactory tract. The other kind is generally 

 situated at some distance from the Glomeruli and has usually more 

 than one protoplasmatic process {olcJ^ fig. 14) which is seen entering 

 a Glomerulus. I am unable to state whether more than one process 

 stands in connection with a Glomerulus, as I have found very few 

 cells of this kind impregnated; it has likewise been impossible to 

 follow the axis-cylinders for any distance, but it is probable that 

 it joins the olfactory tract, as that is the case with similar cells, 

 for instance in the 01. bulbus of the frog {Ca.jal). The Fila olfac- 

 toria enter the Glomeruli and end in an arborisation, as already 

 shown by Retzius (38). 



About the connection between the Bulbus olfactorius and other 

 parts of the brain very little has been published as regards Myxine. 



The only one who mentions the subject is Sanders, who states 

 that the transition from the olfactory lobe to the Cerebrum is quite 

 gradual, that no distinct crura pass into the latter, but that there 

 is a general drift of fibrils in a longitudinal direction. As regards 

 other fishes the subject has been studied by Herrick (19), Fr. Mayer 

 (25) and Edinger (7) and in Mammals chiefly by R. J. Cajal. Her- 

 rick found that the olfactory arrangement in Haploidonotus should 

 be similar to that of the Reptilia. The olfactory tracts should have 

 two branches, the Radix lateralis should spring from the Stratum 

 glomerulorum and pass along to a region of the brain which Herrick 

 (20) identifies with the Lobus hippocamjms, but which part Edinger 

 (7), who has studied the subject further in fishes and reptiles, has 

 given the name of Epistriatura, which name I have adopted. The 

 other root, or the Radix mesalis, should spring from the central 

 portion of the olfactory bulb, pass caudal and dorso-mesad to decus- 

 sate in a ventral portion of the Commissura anterior. In Myxine I 

 found the Bulbus olf, connected with other parts of the brain through 



