622 



SCIENCE 



[N". S. Vol. XLII. No. 1087 



pleurids and seven Eohinometrids has been stud- 

 ied. Special interest attaches to the larva of 

 Echinobrissa recens; it proves to have no likeness 

 to the Spatangoid larv«, but more so to the 

 Clypeastroid larvae, from which it is mainly distin- 

 guished by the rods of its processes being non-fen- 

 estrated. 



A remarkable shortened development was found 

 to obtain in Laganum decogonale and in Toxo- 

 cidaris erythrogrammus. In the former the larval 

 shape is still distinct, although rudimentary; in 

 the latter there is no trace of larval processes, the 

 embryo being simply worm shaped. A similar 

 shortened development will doubtless prove to 

 occur in the Schiaster occurring in the strait of 

 Georgia. 



By the successful rearing of the larvse of a 

 deep-sea species, Lagunum fudsiyama, it has been 

 proved for the first time that typical pelagic 

 larvas may be found among deep-sea forms, and 

 the possibility of studying the embryology of deep- 

 sea forms is shown. 



In other groups of Echinoderms the results are 

 not yet sufficient for definitely establishing family 

 characters in the larvas. An interesting fact is 

 that two species of Asterina, A. pectinifera 

 (Japan), ajid A. regularis (New Zealand), have 

 been found to have typical pelagic larvse. 

 Hydrogen Ion Concentration in Stomach and 



Dwodemwi: J. F. McClendon, University of 



Minnesota. 



The hydrogen ion concentration of the stomachs 

 of normal persons after normal meals was meas- 

 ured every half hour by means of a hydrogen 

 electrode lowered into the stomach or by removing 

 a small sample. The hydrogen ion concentration 

 rises rapidly after injection of the food and 

 reaches a constant level li to 2i hours after fin- 

 ishing the meal. This level varies with the in- 

 dividual and approaches a limit of 1/10 normal 

 H-f. 



The hydrogen ion concentration of the duodenal 

 contents removed with the duodenal tube is about 

 2 XIO-^ 



The hydrogen ion concentration of the infant 's 

 stomach rises slowly after nursing and in one 

 hour is about 6 XlO"". As the stomach empties 

 the hydrogen ion concentration rapidly rises and 

 becomes .01 normal 4 hours after nursing. The 

 hydrogen ion concentration of the infant's duo- 

 denum is about 8 X 10"* or nearly a thousandth 

 normal and is suflicient for peptic digestion. Pep- 

 sin was always present in the infant's duodenum 

 and therefore peptic digestion goes on there. 



Parthenogenesis of the Frog's Egg: J. P. Mc- 

 Clendon, University of Minnesota. 

 In 1911 I showed that the frog's egg may be 

 caused to segment by a momentary electric shock, 

 which takes the place of the spermatozoon. The 

 immediate effect of the electric shock or the 

 spermatozoon is increase in permeability since Na, 

 K, Li, Mg, Ca, a, SO4 and CO3 diffuse out of the 

 egg into the surrounding water at a faster rate. 

 By very careful estimation of the chlorides with 

 the Eichard's nephelometer it was found that 

 twice as much diffused out of the egg that had 

 been stimulated electrically or fertilized as out' 

 of the unfertilized egg in distilled water. This 

 increased permeability continues for 30 hours or 

 perhaps longer. 



The increased permeability protects the egg 

 from swelling. Bachman and Rumstrom supposed 

 the egg was protected by absorption of proteids, 

 but they furnish no grounds for this assumption. 

 The increased permeability of the sea-urchin's 

 egg lasts fifteen minutes after stimulation or fer- 

 tilization and some fish eggs are impermeable to 

 water and salt some time after fertilization. That 

 stimulation and increased permeability are re- 

 lated is supported by the fact that increase in 

 permeability of fish eggs is prevented by anes- 

 thetics. 



Wednesday, August 4, Afternoon Session 

 Joint session of Section P, Zoology, the Ameri- 

 can Society of Naturalists, the American Society 

 of Zoologists, the American Genetic Association 

 and the Eugenics Research Association. 



Demo7istrations 

 In charge of Mart I. McCracken, Stanford 



University 

 Papers: The Sole of Variation and Heredity in 



Evolution 

 David Starr Jordan, Stanford University, pre- 

 siding 

 Heredity and Mutation as Cell Phenomena: R. 

 RuGGLEs Gates, University of London. 

 Heredity consists in the perpetuation of the dif- 

 ference between related organisms. The older 

 definition of heredity as the tendency of like to 

 beget like is incomplete. Variations are divided 

 into three classes, (1) those which are completely 

 inherited, (2) those which are non-inherited, (3) 

 those which are partially inherited ; and these three 

 kinds of variations must have very different evo- 

 lutionary significance. 



