360 ANNALS NEW YORK ACADEMY OF SCIENCES 



features were found indicative of shallow water or wind formation, and 

 the conclusion was reached that the beds were of continental origin. 



The structure of the trap sheet was then taken up, and several peculiar 

 features of structure and texture were described, which are believed to show 

 that a portion of the trap flow covered a lake bed lying in the axis of the 

 continental trough, and other various portions spread over the adjacent 

 shores, and the various facies of the trap are explained upon this theory. 



The Section then adjourned. 



Alexis A. Julien, 



Secretary. 



SECTION OF BIOLOGY. 

 December 9, 1907. 



Section met at 8: 15 P. M., Vice-President Crampton presiding. 



The minutes of the last meeting of the Section were read and approved. 



The following program was then offered: 



Thomas Hunt Morgan, The Effects of Centrifuging the Eggs of 



THE MuLLUSC Cumingia. 

 Raymond C. Osbum, The Replacement of an Eye by an Antenna 



IN AN Insect. 

 Herbert Lang, A Naturalist in British East Africa. 



Summary of Papers. 



Professor Morgan's paper was, in abstract, as follows: Experiments 

 were carried out in order to discover if the cleavage pattern in a type with 

 "determinate cleavage" is governed by the distribution of the visible sub- 

 stances of the egg, and also to discover if the formation of the embryo is 

 possible when the visible inclusions ("organ forming substances") of the 

 protoplasm are artificially shifted. 



The eggs of Cumingia when laid contain the first polar spindle in the 

 center of the egg. The centrifugal force drives the scattered yolk granules 

 to one pole, the pinkish pigment to the opposite pole. Between these two 

 there remains the perfectly clear kinetoplasm, in which the spindle lies, 

 forming an angle with the induced stratification. Its original position has, 

 in fact, been little affected by the movement of the other substances through 



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