420 



SCIENCE. 



[N. S. Vol. XI. No. 272. 



adult and developmental conditions in ver- 

 tebrates generally, probably neither should 

 be regarded as a definitive segment. 



The basis and nature of a schema of the defini- 

 tive encephalic segments : Db. Wilder. 

 " A satisfactory definition of ' Definitive 

 Encephalic Segment ' has not yet been 

 framed, but the best example is the Mesen- 

 cephalon (crura and quadrigeminum). Al- 

 though developed from one ' vesicle,' this 

 apparently includes at least two of the 

 'neuromeres or primitive segments.' Many 

 points are still undetermined. Some were 

 discussed in 1897 in ' What is the Mor- 

 phologic Status of the Olfactory Portion of 

 the Brain ?' Others are indicated among 

 the fifty ' Questions as to the Segmental 

 Constitution of the Brain'; copies of the 

 seven mimeographed sheets bearing these 

 ' questions ' were distributed at the meet- 

 ing and will be sent to those interested. 

 The following conclusions are regarded as 

 sound : — The provisional schema of the 

 definitive segments should be based upon 

 adult rather than developmental conditions. 

 The definitive segments need not be struc- 

 turally or developmentally identical. They 

 need not coincide with either, (a) the 

 primitive neuromeres, or (6) the primary 

 encephalic vesicles, (c) the secondary vesi- 

 cles. No species or group should be ig- 

 nored. The presumption is in favor of 

 generalized forms, and not in favor of forms 

 merely because they are available for other 

 purposes. When both naturalness and 

 convenience are taken into account, the 

 best provisional schema corresponds mainly 

 with the one indicated in the table on p. 29 

 of the Proceedings of this Association for 

 May, 1897." 



Is neuron available as a designation of the cen- 

 tral nervous system ? Dr. Wilder. 

 " Neuron (from to veupov) was proposed 



by me in this sense in 1884 (iV. Y. 



Med. Jour., Aug. 2, p. 114), and emploj'ed 



in the same Journal, March 28, 1885, p 

 356 ; in addresses before the Amer. Neurol 

 Assoc; {Jour. Nerv. and Ment. Dis., July 

 1885) ; Amer. Asso. Adv. Sci. Proceedings 

 1885, and in the second edition of ' Ana 

 tomical Technology,' 1886. It has been 

 adopted by McClure, Minot, Waters and 

 others. The reasons for its abandonment 

 in 1889 for neuraxis, as stated in the Pro- 

 ceedings of this Association for 1895, p. 44, 

 and Ref. Handbook of Med. Sci., IX., 100, 

 now seem to me inadequate. Neuroiiisthe 

 basis of Pleural (as applied to aspect, folds^ 

 furrow, and canal) and of neurenteric and 

 other compounds, and it is the natural cor- 

 relative of enteron (entire alimentary canal) 

 and of axon (notochord or primitive skele- 

 tal axis). Not until 1891 did Waldeyer 

 propose neuron for the nerve-cell and its 

 processes ; not until 1893 did Shafer apply 

 it to the axis-cylinder process. As with 

 tan-US and cilium the context would com- 

 monly avert confusion between the macro- 

 scopic and microscopic significations of 

 the word in a given case. The compounds 

 macroneuron and microneuron might be em- 

 ployed if necessary, or (as suggested by 

 Barker, p. 40), the histologic element might 

 be designated by neurone, as if from vsupdv. 

 Note. — The question is now further com- 

 plicated by Van Gehuchten's adoption of 

 ' Neuraxe ' as the title of a new journal of 

 neurology. 



Polydactylism and Syndactylism : Dr. Shep- 

 herd, of Montreal. 



Dr. Shepherd showed a series of skia- 

 grams and photographs illustrating some of 

 the deformities of the digits which he had 

 met with. The first case was that of a j'oung 

 man aged 21, who had six digits on each foot 

 and hand, and they were so arranged that 

 the deformity would not be noticed unless 

 attention was especially attracted to it ; 

 there was a gradual diminution in the size 

 from the middle finger to the supernumer- 



