May 15, 1914] 



SCIENCE 



731 



TABLE III 



(Atnhlystoma larv£e) 



If we wish to institute a comparison between 

 the water content of the embryonic nervous 

 system and the corresponding adult structure, 

 it is more correct to use the water content of 

 the cord, for this is less differentiated than 

 the brain and consequently more nearly re- 

 sembles the larval condition. Donaldson'^ has 

 given the water content of 12 cords of Rana 

 pipiens. The average is 80.5 — identical with 

 my value of 80.1 for the larval system. 



Comparisons were also made between the 

 water content of the anterior and posterior 

 ends of the embryonic nervous system. For 

 this purpose I divided 125 isolated larval nerv- 

 ous systems of Amblystoma in two, as accu- 

 rately as possible, in the medullary region. 

 Dry substance determinations of the separated 

 portions were then made with the following 

 results : 



TABLE IV 



{Amblystoma) 



These results are in the same sense as 

 those reported by Donaldson,^ as the water 

 content of the brain of an adult Rana pipiens 

 is 84.9 per cent., or 4.4 per cent, higher than 

 that of the cord. My results on Amblystoma 

 indicate that the larval brain contains more 

 water than the attached cord. 



1 Donaldson, Henry H., ' ' Further Observations 

 on the Nervous System of the American Leopard 

 Frog, Sana pipiens, etc.," Journal of Comparative 

 Neurology and Psychology, Vol. 20, p. 2. 



2 Loc. cit., p. 2. 



We may conclude therefore that the nervous 

 system as a whole has a specific capacity for 

 holding water and that this specificity exists 

 from the beginning. This can be the outcome 

 of nothing other than a physical-chemical 

 specificity, and we must suspect that the nerv- 

 ous system differentiates as a morphological 

 entity, because its chemical differentiation 

 endows it with a specific capacity for holding 

 water. Moreover, two regions as sharply dis- 

 tinct, morphologically and physiologically, as 

 brain and cord have each their own specific 

 capacities, and these although not differing as 

 widely, perhaps, as in the adult, are neverthe- 

 less at variance in the embryo in the same 

 sense. The thought lies near at hand, there- 

 fore, that the gross structural diilerences be- 

 tween brain and cord brought about during 

 the course of development are definitely related 

 to the fact that their respective rudiments 

 maintain each its own specific relation between 

 the amount of dry substance and the amount 

 of water. 



Otto Glaser 



Univeesity op Michigan, 

 April 3, 1914 



CONFERENCE ON INDIVIDUAL PSYCHOL- 

 OGY 



Former pupils of the department of psychology 

 of Columbia University held a reunion and confer- 

 ence at the university, on April 6-8, and on the 

 latter date gave a dinner to Professor James Mc- 

 Keen Cattell in celebration of the twenty-fifth an- 

 niversary of his first appointment as professor of 

 psychology. This first appointment was at the 

 University of Pennsylvania, and Professor Wit- 

 mer, of that institution, one of Professor Cattell 's 

 earliest students, participated in the dinner. On 

 this occasion a volume entitled ' ' The Psycholog- 

 ical Researches of James McKeen Cattell : A Re- 

 view by Some of His Pupils," written by Messrs. 

 Thorndike, Wells, Henmon, Dearborn, HoUing- 

 worth and Woodworth, was presented to Professor 

 Cattell. 



The program of the Conference follows: 



Monday, April 6, at 3 P.M. 

 Chairman, Professor Cattell 

 ' ' Individual Differences in Sense Discrimina- 

 tion": V. A. C. Henmon (Ph.D., 1905), professor 



