RECORDS 479 



early cleavage stages, are the ancestors of cells which occupy 

 particular positions in later stages. Following Conklin's 

 terminology ('97) the cleavage may be characterized as "de- 

 terminate." This conclusion is completely opposed to the re- 

 sults of the earlier investigators of cirripede development. 



Gastrulation is of the epibolic type, and is the result of the 

 extension of the ectoblastic blastoderm over the entoblastic 

 yolk-macromere. The blastodern usually closes over the 

 blastopore during the sixth cleavage (62 cells). The blastopore 

 is identified as marking the ventral and posterior of the future 

 embryo. 



In the general features of the late development of the embryo 

 the results of this investigation confirm those of some earlier 

 workers. 



On account of the discomfort caused by the low temperature 

 of the room the second paper of the evening was omitted by 

 general consent. 



On motion of Professor F. E. Lloyd, a committee of one 

 was appointed to communicate with the Recording Secretary in 

 regard to the unsatisfactory heating arrangements, with a re- 

 quest that a complaint be lodged against the culpable parties. 



Mr. Lloyd was asked to serve as the committee. 



Adjournment followed. 



Francis E. Lloyd, 



Secretary. 



GEOLOGY AND MINERALOGY. 

 April 16, 1900. 



Section met at 8:20 P. M., Dr. A. A. Julien presiding. 



The minutes of the last meeting of Section were read and ap- 

 proved. 



The following program was then offered : 



R. Ellsworth Call, Some Preliminary Notes on Crystal 

 Growths in Mammoth Cave. (Illustrated by Lantern Slides.) 



E. 0. Hovey, Scenery of the Harney Peak District in 

 the Black Hills, S. D. (Illustrated by Lantern Shdes.) 



