xii Journal of Comparative Neurology. 



nating cell. This chromatin divides into two parts, each containing 

 iron and phosphorus, but the one is oxyphile and remains in the nu- 

 cleus, while the other is basophile and diffuses into the cell body and 

 becomes the Nissl granules. A portion of the nuclear chromatin, 

 however, remains unmodified about the nucleolus. The Nissl gran- 

 ules are regarded as morphological elements, composed of one .sub- 

 stance which has the same refractive index during life as the cytoplasm. 



c. J. H. 



Histogenesis of Peripheral Nervoiis S»steiu iii Teleosts.' 



This careful research contributes welcome data on one of the 

 vexed questions of the day. The development of the salmon is traced 

 step by step until the peripheral nervous system is fully laid down. 

 The exposition is characterized by unusual clearness of statement and 

 the figures in particular are very convincing. The author supports 

 throughout the doctrine of His that every nerve fiber arises from a 

 single cell, as opposed to the cell-chain theory. He finds, it is true, 

 cells migrating out from the spinal cord with the ventral root fibers, 

 such as are described by the advocates of the latter theory. These 

 cells, however, follow the outgrowth of the axis cylinders of the ven- 

 tral roots and Dr. Harrison's interpretation of them is different from 

 that of any of the other recent students of this problem. In fact, he 

 thinks it probable that they enter into the formation of motor sympa- 

 thetic ganglia. 



The neural crest is carefully described and its peculiar develop- 

 ment in the teleosts put into relation with its simpler history in other 

 vertebrates. The history and significance of the giant cells, or Hinter- 

 zelle, are treated very fully. They arise in that portion of the medul- 

 lary cord which corresponds to the neural crest and differentiate into 

 two forms. The first sends out a T-process, one limb of which ascends, 

 the other descends in the dorsal column. The second form is similar, 

 but sends out in addition to the other processes a peripheral process 

 which enters the dorsal root and terminates as a sensory fiber in the 

 skin. This peripheral distribution is a primitive one, and these cells 

 are homologous with spinal ganglion cells, also with the middle-sized 

 (not the colossal) bipolar ganglion cells of Amphioxus, with the dorsal 

 cells of Petromyzon and with the the transitory nerve cells of Elasmo- 

 branchs. They are sensory elements which fail to wander out into the* 



' Harrison, Ross Granville. Ueber die Histogenese des peripheren 

 Nervensystems bei Salmo salar. Archiv f. niikr. Anat., LVII, 190 1. 



