400 CHARLES HILL, 



pears below.) He finds no neuromeres in the encepbalon cepbalad 

 to the mid-brain but assumes that in ancestral forms there was a 

 segmental condition of this region. 



Hoffmann, 'SS, reports 7 segments present in the hind-brain 

 of Lacerta and Tropidonotus^ adding one cephalic segment caudad to 

 the 6 neuromeres that Orr described in Anolis. The author differs 

 somewhat from Orr as regards the relationship of the cranial nerves 

 to these segments. 



Miss Platt, '89, divides the encepbalon of the embryonic chick 

 into 7 primary segments. Five of these are in the medulla, the 

 cerebellum constitutes one and the primary fore-brain and mid-brain 

 one. From her descriptions, it appears that the "neuromeric segmen- 

 tation" has been confused with the division of the front end of the 

 neural tube into brain vesicles. 



McClure, '90, demonstrates neuromeric segmentation throughout 

 the neural tube and also verifies, in the chick and lizard, Orr's hind- 

 brain neuromeres but finds only 5 segments in this region in Am- 

 Uystoma. He finds 2 neuromeres in the fore-brain and assumes, 

 from the examination of figures, the existence of 2 in the mid-brain. 



Waters, '92, decides that there are 3 neuromeres in the 

 fore-brain of Teleosts; 2 in the mid-brain and 6 in the hind-brain, 

 making a total of 11 in the entire encepbalon. He confirms the 

 observation of McClure regarding the presence of but 5 neuro- 

 meres in the hind-brain of Amblystoma but suggests that the reduction 

 is probably due to a fusion of two segments. 



Froriep, whose contributions like those of Kupffer extend over 

 a number of years, finds in embryos with the neural groove widely 

 open, 5 segments in the cephalic plate of Triton cristatiis and 4 

 in Salamandra maculosa. In 1891, he finds two segments in the 

 diencephalon and 3 in the mesencephalon of the mole and assigns 

 to them a metameric value. The next year he withdraws from this 

 position and says: "the segmentation is merely passive mechanical 

 results of rapid longitudinal growth in a limited space and has there- 

 fore no morphological significance." The early neural segments de- 

 tected by Kupffer m Salamandra atra he believes to be the result 

 of underlying mesoderm-somites and concludes that "The jointing of 

 the Vertebrate body is dependent upon the middle germ layer". 



Herrick, '92, finds 6 neuromeres in the medulla of Ophidian 

 embryos and makes the very pertinent statement: "if neuromeres once 



