122 CARNEGIE INSTITUTION OF WASHINGTON. 



Abnormalities in Development Resulting from Centrifuging Eggs, 

 A. M. Banta and R. A. Gartner. 



As a by-product of some chemical studies, interesting abnormalities 

 in developing embryos of frogs were induced which are worth recording, 

 though they have no obvious significance for heredity. Dr. Banta and 

 Dr.Gortner "centrifuged" some embryos oiRana sylvatica at the blasto- 

 pore stage, subjecting them to 1,350 times the pressure of gravity for 

 2 minutes, and an accessory tail-like appendage developed in all of the 

 survivors — usually one accessory tail, but occasionally two to four. The 

 accessory tails were scattered along the mid-ventral region and had a 

 typical tail-like structure. In some " centrifuged eggs " of the salaman- 

 der, Amhy stoma, the front end of the head, sometimes back as far as 

 the gills, failed to develop. The interest of this observation lies in the 

 demonstration that the hereditary determiners for development work 

 out their destined end only when maintained in certain proper spatial 

 relations. When displaced by the centrifugal machine they influence 

 the production of their appropriate organs in abnormal positions. By 

 reducing the abnormal pressure a point is reached where the determiners 

 are not displaced and, hence, no abnormal development occurs. The 

 limit serves, in a way, to measure the relative strength of hereditary 

 and environmental forces in the given case of development. 



BIOCHEMICAL PROCESSES IN HEREDITY. 



Chemistry of Ontogeny, R. A. Gartner. 



Development is a series of chemical processes which is directed by the 

 presence of certain determiners that afford the hereditary control. A 

 beginning has hardly been made upon the study of the chemical changes 

 that accompany the morphological changes of ontogeny, yet this 

 problem is of the greatest importance for evolution. For, just as the 

 changes in form exhibited by an organism during ontogeny give some 

 idea of the successive forms of the ancestors of the individual from the 

 earliest to more recent times — and thus epitomizes the course of evolu- 

 tion of the species — so the chemical changes during ontogeny may well 

 be considered to epitomize the evolution of the chemical characteristics 

 of the species. And as there is much reason for thinking that the 

 morphological changes have depended upon the chemical, it is obvious 

 that the proposed study is of the greatest importance for evolution. 

 The earlier experiments of Dr. Gortner on this subject were described 

 in last year's report. Dr. Gortner continued this work by comparative 

 analyses of the eggs and the newly hatched larvie of the giant sala- 

 mander, Cryptohranchus alleganiensis. The total dry weight diminishes 

 by 1.6 per cent, due to loss of carbon dioxide and water, for the total 

 nitrogen does not change. There is a gain of fats to the extent of 14 



