October 6, 1916] 



SCIENCE 



509 



infer, therefore, that the embryonic brain, like 

 that of the adult, also has a water-content 

 higher than that of the cord at the same age. 



If this is indeed correct, and, moreover, if 

 nuclear volume varies with the water-content 

 of the cell, and, furthermore, if fixation does 

 not destroy or completely reverse the volu- 

 metric relations, one would expect the nuclei in 

 the anterior end of an embryonic nervous 

 system to be larger than those in the posterior. 



In Cryptobranchus embryos such compari- 

 sons are easily made. The nuclei are large so 

 that errors, inevitably committed in deter- 

 mining their volumes, are relatively small. 

 Certain precautions however are essential. 

 Thus nuclei in various stages of mitosis must 

 obviously be excluded. Also, since the rest- 

 ing nucleus is ovoid in shape, it is necessary to 

 consider only those similarly oriented with 

 reference to the plane of section. Absolute 

 volumes are, of course, not practicable, nor 

 are they requisite. All that the theory de- 

 mands is that the average size of the nuclear 

 sections in the regions which had the higher 

 water-content shall be greater than those in the 

 regions in which the water-content was lower. 

 Tracings of some 2,800 nuclei whose outlines 

 on paper were cut out with scissors and 

 weighed under uniform conditions of atmos- 

 pheric moisture, give results remarkable for 

 their uniformity. 



The absolute regularity of the ratios based 

 on Cryptobranchus, and on the control observa- 

 tion on the thirty-six hour chick, convinced 

 me that nuclear size, even in preserved mate- 

 rials, can be utilized as an index of original 

 water-content. If now, the absorption of water 

 is itself an index to the surface alteration to 

 which I attribute the change in shape under- 

 gone by the cells during involution, then the 

 nuclei of the lateral curling edges in any 

 given section should on the average be larger 

 than those in the, as yet, unfolded center. 

 This, as indicated in the last division of Table 

 VI., is true for Cryptobranchus. 



Since this expectation has been fulfilled, I 

 feel that the problems involved in the autono- 

 mous folding of the nervous system, and by 

 implication, also involved in such other auton- 



omous foldings as that of the entodermal plate 

 in typical invaginate gastrulation, have begun 

 to merge with the physical-chemistry of the 

 tissues concerned, and the conditions to which 

 their constituent cells are subjected at various 

 periods of development. 



O. C. Glaser 

 University of Michigan 



SOCIETIES AND ACADEMIES 



THE AMERICAN MATHEMATICAL SOCIETY 



The twenty-third summer meeting and eighth 

 colloquium of the society were held at Harvard 

 University during the week September 4-8, 1916. 

 Monday and Tuesday were devoted to the sum- 

 mer meeting proper, two sessions being held on 

 each day for the presentation and discussion of 

 papers. The colloquium opened on Wednesday 

 morning and extended to Friday afternoon. 

 Courses of lectures were given by Professor G. C. 

 Evans, of Bice Institute, on ' ' Topics from the 

 theory and applications of functionals, including 

 integral equations," and Professor Oswald 

 Veblen, of Princeton University, on "Analysis 

 situs. ' ' 



Ninety-nine were in attendance. President E. 

 W. Brown occupied the chair, being relieved by 

 Vice-presidents E. B. Hedrick and Virgil Snyder. 

 The council announced the election of the follow- 

 ing persons to membership in the society: Mr. 

 Herman Betz, Cornell University; Mr. J. A. Big- 

 bee, High School, Little Eoek, Ark.; Mr. Hillel 

 Halperin, Vanderbilt University; Dr. J. E. Kline, 

 University of Pennsylvania; Professor J. J. Luck, 

 University of Virginia; Dr. P. J. McMackin, Dart- 

 mouth College. Seven applications for member- 

 ship in the society were received. 



Through the generosity of Harvard University 

 the freshman dormitories and dining room were 

 thrown open for the use of the society during the 

 meeting. On Monday noon the members were 

 shown the collection of mathematical models be- 

 longing to the university. On Wednesday after- 

 noon a visit was paid to the university library, and 

 on Wednesday evening to the observatory. Eeso- 

 lutions were adopted at the meeting expressing 

 the thanks of the society for the hospitality of the 

 university and its officers. 



Fraternal greetings were exchanged by cable 

 with the Scandinavian mathematicians assembled 

 at Stockholm. A vote of congratulation was 

 tendered to the secretary on his twenty-first year 

 of service in that capacity. 



