144 Joi'HNAL OF Comparative Nei'rologv. 



a slight ventral curvature into the median part of medio- 

 caudad projection of the cortex, and thence across to the 

 caudo-lateral portion. The superior commissure is relatively 

 stronger than its neighbor, and it would appear that the two 

 are especially distinct in animals like the lizard, where the 

 epiphysis is highly developed." A comparison of the re- 

 searches in the mammalian brain with those in the brains of 

 the lower vertebrates, would lead us to conclude that the 

 median commissure [see '■' p. 63] in the one and the supra- 

 commissure in the other, though not entirely homologous, are 

 still in their structure and in their connections, capable of 

 similar functions. It is Herrick's opinion ['^ p. 36] that 

 instead of considering that the supra-commissura is divided 

 into two parts in the amphibians and reptiles, we would do 

 better to reccognize two originally distinct commissures. 



Mcyncrfs Bundle. — Mayser [' p. 357] has told us that in 

 the fishes this bundle consists of non-medullary fibres. It is 

 of a single nature, running from the habenular ganglion 

 ventrad and caudad. Breaking through the commissure of 

 the fibrce ansulatae, it divides into many fascicles. It enlarges 

 at the point where an addition of fibres is made from the 

 wall of the aqueduct. Most investigators have traced the 

 bundle only as far as the inter-peduncular ganglion, but in 

 the amphibians Osborn has found fibres of it running past 

 this point, and Ahlborn [' p. 2S5] claims that in the brain of 

 Petromyzon he has traced them even into the metencephalon. 

 Wright's investigations with Amiurus lead him to conclu- 

 sions similar to those of Mayser just stated above. Gorono- 

 witsch ['" p. 551] traced these fibres caudad only as far as 

 the proximal boundary of the inter-pedunclar ganglion. In 

 the mammalian brain the course of Meynert's bundle is not 

 such a simple one. The course [Honegger,'' p. 407] in some 

 of the mammals is quite different in detail from that in others. 

 The main cause of the difference is the large development of 

 the" red nucleus " in some of these brains. In man the bun- 

 dle is very strongly deflected from its course as it passes the 



