May 12, 1905.] 



SCIENCE. 



741 



]\Iaukice Frechet: ' Sur les operations lin- 

 eaires (deuxi&nie note).' 



E. Kasner: ' Surfaces whose geodesies may be 

 represented in the plane by parabolas.' 



Max Mason : ' The doubly periodic solutions of 

 Poisson's equation in two independent variables.' 



0. Veblen: 'Definition in terms of order alone 

 in the linear continuum and in well-ordered sets.' 



S. Epsteen and J. H. Maclagan-Wedderburn : 

 ' On the structure of hypercomplex number sys- 

 tems.' 



E. H. Moore: 'On a definition of abstract 

 groups.' 



E. V. Huntington : ' Note on the definitions of 

 abstract groups and fields by sets of independent 

 postulates.' 



L. E. Dickson : ' Definitions of a group and a 

 field by independent postulates.' 



L. E. Dickson : ' On semi-groups and the gen- 

 eral isomorphism between finite groups.' 



E. V. Huntington : ' A set of postulates for 

 ordinary complex algebra.' 



H. F. Blichfeldt: 'On imprimitive linear ho- 

 mogeneous groups.' 



SOCIETIES AND ACADEMIES. 

 THE SOCIETY FOB EXPERIMENTAL BIOLOGY AND 

 MEDICINE. 



The eleventh regular meeting of the Society 

 for Experimental Biology and Medicine was 

 held in the zoological laboratory of Columbia 

 University, on Wednesday evening, April 19. 

 The president, Edmund B. Wilson, was in the 

 chair. 



Memhers present. — Adler, Auer, Calkins, 

 Emerson, Gies, Hatcher, Jackson, Lee, Levene, 

 Levin, Lusk, Meltzer, Morgan, Murlin, Rich- 

 ards, Salant, Sherman, Torrey, Wallace, Wil- 

 son, Wolf, Tatsu. 



Memhers elected.- — Harlow Brooks, W. B. 

 Cannon, A. J. Carlson, R. 6. Harrison, A. P. 

 Mathews, G. H. Parker, A. E. Taylor. 



abstracts of reports of ORIGINAL 

 INVESTIGATIONS.* 



The Relation Between Normal and Abnormal 

 Development of the Frog's Egg: T. H. 

 Morgan. 



* The abstracts presented in this account of the 

 proceedings have been greatly condensed from ab- 

 stracts given to the secretary by the authors 

 themselves. The latter abstracts of the reports 

 may be found in current issues of American 

 Medicine and Medical News. 



The method of development of the frog's 

 egg may be changed by a number of external 

 conditions, e. g., treatment with salt solutions 

 of definite strengths, variations of tempera- 

 ture, deprivation of oxygen, treatment with 

 carbon dioxid, subjection to 180 revolutions 

 per minute, etc. The effects of such external 

 agents are not gradual, i. e., corresponding in 

 degree to the increasing strength of the agent 

 employed, for no effects appear up to a certain 

 point, when suddenly the agent begins to act. 

 Increasing the strength of the agent above 

 this point increases the effect very slightly. 

 The most plausible explanation of this mode 

 of behavior in most of the cases is as follows: 

 The agents act by coagulating certain parts 

 of the egg, thereby preventing their further 

 development. Other parts of the egg that 

 are made up of different colloids or of dif- 

 ferent concentrations of colloid, remain im- 

 affected, and proceed to carry out their devel- 

 opment as far as the presence of the injured 

 region allows. 



The author referred particularly, however, 

 to a second point of special interest: Despite 

 the great diversity in the form of the abnor- 

 mal embryos, most of them may be reduced to 

 modifications of the same type. He stated 

 that the abnormal embryo develops in the 

 material of the upper hemisphere, while the 

 normal embryo develops over the lower hemi- 

 sphere. Two interpretations of this difference 

 seem possible. Either the material is toti- 

 potent and an embryo may develop anywhere 

 in the egg, appearing in the less injured re- 

 gions; or the material for normal and abnor- 

 mal development is the same and becomes 

 carried downward, during the early stage of 

 normal development, from the upper into the 

 lower hemisphere. A test of these alternatives 

 showed that when the two upper anterior 

 blastomeres are removed, the head end of the 

 embryo is defective; when the two upper pos- 

 terior blastomeres are removed the posterior 

 end sometimes shows defects. When all four 

 of the upper blastomeres are removed no em- 

 bryo develops, although the blastoporic rim 

 may appear near the equator of the egg, the 

 gastrulation process may begin and the dif- 



