!12 



SCIENCE. 



[N; S. Vol. IX. No, 218. 



The subterranean egg-burrow of this sal- 

 tatory urodeles resembles somewhat closely 

 that of Ichthyo'phis. The eggs are retained 

 in a cluster and attended and kept moist- 

 ened, probably with urine, by the female. 

 A series of embryos taken from a single bur- 

 row will shortly be described. 



New Facts regarding the Development of the Ol- 

 factory Nerve. W. A. Locy. 



The early embryonic history of the olfac- 

 tory nerve is known. There has been little 

 advance in this direction since the appear- 

 ance of Marshall's paper in 1S7S, who gave 

 the history of the nerve prior to the forma- 

 tion of the lobe and anticipated by sugges- 

 tion most of the views since expressed re- 

 garding its nature and relationships. The 

 chief advances have been made in deter- 

 mining the source of the fibers (His, Disse 

 and others), and in the minute structure of 

 the olfactory lobe, ganglion, etc. (Cajal, 

 Retzius and others). But, in the meantime, 

 the early embryonic history has not been 

 elucidated, and, even to-day, we do not 

 possess the complete history of this nerve in 

 any one animal. 



This paper presented in outline the his- 

 tory of the olfactory nerve in Acanthias 

 from its earliest appearance to adult condi- 

 tions, embracing (a) the embryonic history 

 of the olfactory nerve prior to the formation 

 of the lobe, and (6) the formation of the 

 olfactory lobe, its various transformations, 

 and the subsequent history of the nerve. 

 The chief point of interest consists in dem- 

 onstrating a hitherto unrecognized olfac- 

 tory nerve, and determining its history and 

 relationships to the olfactory bundle. The 

 new nerve arises from the summit of the 

 forebrain near the median plane, and passes 

 laterally into communication with the main 

 olfactory and thence into the olfactory cup. 

 It is the iirst one to appear and may, there- 

 fore, be primitive. It is ganglionated. It 

 was discovered by dissections of very small 



embryos — it lies in such a position that its 

 relationships would not be appreciated by 

 study of sections made in any of the con- 

 ventional planes. 



There are two distinct, widelj- separated 

 connections existing simultaneously be- 

 tween the olfactory epithelium and the 

 brain-wall, one is dorsal and median (the 

 new nerve) and the other is lateral. The 

 latter is complex, consisting of two main 

 divisions. The new nerve can be demon- 

 strated in specimens, as early as 6-8 mm. 

 in length. The two brain connections are 

 well seen in embryos 16 mm. and upwards ; 

 they are very evident from 20mm. forwards. 

 The lobe begins in specimens about 25mm. 

 long ; it is still small at 38mm., but well de- 

 veloped at 44 mm. and upwards. The fibers 

 of the new nerve were traced into the ol- 

 factory epithelium. It was also shown to 

 perish in the adult. 



Review of Recent Evidence on the Segmentation 

 of the Primitive Vertebrate Brain. W. A. 

 LocY. (Read by title.) 



The Metameric Value of the Sensory Compo- 

 nents of the Cranial Nerves. C. Judson 

 Hekrick. 



The primary segmental or brauchiomeric 

 nerve is conceived as comprising four com- 

 ponents : somatic motor, viscero-motor, so- 

 matic sensory (general cutaneous) and 

 viscero-sensory (communis). No cranial 

 nerve of any gnathostome vertebrate has 

 retained all these components. 



In the head each sensory component, as 

 a physiological adaptation, has been con- 

 centrated so that all its fibers tend to be 

 related to a single center in the brain — the 

 fasciculus communis (f. solitarius) and 

 chief vagus nucleus in the case of the vis- 

 ceral sensory and the spinal fifth tract and 

 related nuclei, chief sensory trigeminal n. 

 and n. funiculi, in the case of the somatic 

 sensory. This involves reduction of each 

 component in some segments and hyper- 



