28o Journal of Comparative Neurology. 



is describing it as it appears in the human subject. Edinger, 

 after remarking that certain of the fibres of the posterior 

 commissure curve caudad, continues: " These fibres, together 

 with others which arise in the depth of the inter-brain, are 

 met with as a fine fasciculus ventrad of the anterior oculo- 

 motor nidulus. As we pass back this fasciculus progressively 

 increases. There are added to it numerous fibres from the 

 nucleus of the oculo-motor. We shall, from :iow on, meet 

 with the triangular cross-section of this bundle, which is 

 composed of fibres from such various regions on every trans- 

 verse section of the brain, from the corpora quadrigemina 

 down to the beginning of the spinal dord. This bundle has 

 been called the fasciculus longitudinalis posterior. Inasmuch 

 as fibres are given off" along the whole course of this bundle 

 to the nerve-nuclei, as can be plainly seen in embryos of the 

 sixth to seventh month, when few other fibres are medullated, 

 and, as this bundle projects further back than the nucleus of 

 the abducens, it is probable that the fasciculus longitudinalis 

 posterior not only contains the fibres of communication be- 

 tween the nuclei of the ocular muscles, but that it also con- 

 tains fibres to other cranial nerves. Flechsig is also of this 

 opinion," etc. 



Honegger's solution, written contemporaneously, cer- 

 tainly is not in accord with the above. This author con- 

 siders that this tract does not give oft' fibres to the posterior 

 commissure. He has also demonstrated that a portion of the 

 fibres of the posterior longitudinal fasciculus pass to the 

 mammillary body, and that other fibres of this bundle decus- 

 sate in the ventral portion of the diencephalon. 



In the avian brain that portion of this fasciculus which 

 lies cephalad of the oculo-motor nidulus consists of a few 

 scattered fibres. Cephalad, these fibres terminate abruptly, 

 near the posterior commissure. Passing caudad, between the 

 oculomotor and the trochlear niduli, these few fibres become 

 a large bundle. From this point to the myelon there is a 

 progressive increase in the size of this bundle. A short dis- 



