386 



SCIENCE 



[N. S. Vol. XXXIII. No. 845 



mean free path of its molecules at some par- 

 ticular pressure or pressures, may possibly af- 

 ford the necessary conditions for fortuitous 

 resonance, with development of some slight 

 amount of heat by the increased violence of 

 inter-molecular collisions. I have done much 

 experimental work on these lines during the 

 past year, but, notwithstanding refinement of 

 method and manipulation, the results have 

 thus far been unsatisfactory. The work is still 

 in progress, however, and investigation of 

 other phenomena is contemplated. 



Charles F. Brush 

 Cleveland, Ohio 



AMERICAN SOCIETY OF ZOOLOGISTS 

 EASTERN BRANCH 



The Eastern Branch of the American Society 

 of Zoologists held its annual meeting on December 

 27-30, 1910, inclusive, at Cornell University, 

 Ithaca, N. Y., in conjunction with the American 

 Society of Naturalists, the American Association 

 of Anatomists and the Society of American Bac- 

 teriologists. 



The following officers were elected: 



President — H. V. Wilson, University of North 

 Carolina. 



Vice-president — H. E. Crampton, Columbia Uni- 

 versity. 



Secretary -treasurer — ^Raymond Pearl, Maine 

 Agricultural Experiment Station. 



Additional Member of Executive Committee — 

 R. G. Harrison, Yale University. 



The following persons were elected members of 

 the American Society of Zoologists at this 

 meeting: Dr. Alice M. Boring, University of 

 Maine; Dr. 0. A. Johannsen, Maine Agricultural 

 Experiment Station; Professor R. E. Sheldon, 

 University of Pittsburgh; Professor A. E. Lam- 

 bert, State Normal School, Framingham, Mass.; 

 Dr. R. C. Schiedt, Franklin and Marshall College ; 

 Dr. Sergius Morgulis, Harvard University; Pro- 

 fessor E. W. Gudger, State Normal College, 

 Greensboro, N. C. ; Dr. A. M. Banta, Carnegie 

 Institution, Station for Experimental Evolution; 

 Professor 6. G. Scott, College of the City of New 

 York. 



A committee was appointed to prepare a resolu- 

 tion on the death of Professor C. O. Whitman. 

 This resolution will be published in a later num- 

 ber of Science. 



The following papers were presented at the 

 meeting, either in full, or by title: 



The Spermatogenesis of the Opossum: H. E. 



JOEDAN, University of Virginia. 



An accessory chromosome and chondriosomes 

 are the structures of special interest. Metaphase 

 plates of dividing spermatogonia contain 17 rod- 

 shaped chromosomes (diploid group; 16 auto- 

 somes, 1 monosome). A chromatin- (chromo- 

 some) nucleolus is present during the growth 

 period (including synizesis and synapsis) in- 

 variably at that point near the nuclear membrane 

 next the eentrosphere. The first numerical reduc- 

 tion results from a pairing end to end (telosyn- 

 apsis) of the 16 autosomes. The haploid chro- 

 mosome group thus contains 9, the accessory 

 recognizable by its larger size and bipartite form. 

 During metakinesis (reduction division) the ac- 

 cessory chromosome passes undivided, and in ad- 

 vance of the ordinary chromosomes, to one pole. 

 Two types of secondary spermatocytes result: one 

 with 9, the other with 8 chromosomes. During 

 the brief resting phase one type has a chromatin- 

 nucleolus, the other lacks this structure. A sec- 

 ond numerical reduction has occurred — a phenom- 

 enon previously described by Bardeleben (1898) 

 for man, and quite recently by Guyer for certain 

 birds — giving rise to hemioid groups containing 

 5 and 4 chromosomes, respectively. The ensuing 

 division is equational. In the early spermatid- 

 phase a resolution takes place giving 9 and 8 

 chromosomes, respectively. A dimorphism of 

 spermatozoa thus results. Chondriosomes (mito- 

 chondria) appear in early postsynaptic stages 

 (probably as chromidia passed out of the nu- 

 cleus). A direct continuity is demonstrable be- 

 tween the chondriosomes and the spiral filament 

 of the middle piece of the spermatozoon. No twin 

 spermatozoa, such as Selenka described in the 

 vas deferens of the opossum, appear in the testes 

 studied. 



The complete paper will appear in the Archvv 

 fur Zellforschung. 



The Germ Cell Determinants of Beetles' Eggs: 

 RoBEBT W. Hegner, University of Michigan. 

 This report is based on the results of experi- 

 ments in killing parts of the eggs of some chrys- 

 omelid beetles. The posterior ends of freshly-laid 

 eggs contain a disc-shaped mass of granules that 

 stain like chromatin. These granules are taken 

 up by the cleavage products that encounter them; 

 these cleavage products later become germ cells. 

 For this reason the granules have been called 

 germ-cell determinants. When the posterior ends 

 of freshly-laid eggs are killed with a hot needle, 

 thus preventing the granules from taking part in 



