98 RECORDS 



sisting chiefly in the elongation of organs which would carry 

 the chlorophyl screens and reproductive bodies up into the 

 light. Light is not necessary to the motility of protoplasm or 

 to the activity of the motor mechanisms of such plants as Mi- 

 mosa ; the condition known as darkness-rigor does not exist. 

 Appearances commonly supposed to be due to rigor of dark- 

 ness are pathological phenomena occasioned by the disintegra- 

 tion of chlorophyl and other substances. 



Light may exert a direct chemical (disintegrative) effect upon 

 the constructive material of the cell, but it does not retard 

 growth ; on the contrary, it accelerates growth among the algae. 

 Evidence that light exercises a paratonic influence upon plants 

 is not at hand, and no observations could be found by the 

 speaker supporting the conclusion that a similar retarding influ- 

 ence of light upon growth occurs among animals. 



In discussion of Dr. MacDougal's paper, Mr. M. A. Bigelow 

 called attention to some experiments made by him, under the 

 direction of Professor C. B. Davenport, to determine the influ- 

 ence of light upon embryonic development and post-embryonic 

 growth in Amphibia. Light does not retard, but rather accel- 

 erates developmental processes, the effective rays being red in 

 embryonic and blue during post-embryonic stages. 



Dr. Mayer stated that in 1898 he had discovered a pentam- 

 erous Hydromedusa at the Tortugas, Florida, and had named 

 it Pseiidoclytia pentata. In this form there are five radial canals, 

 five lips, and five gonads 72° apart, instead of four of these 

 various organs at intervals of 90°, as in other Hydromedusse. 

 In its anatomy it is related to the genus Epenthesis, being very 

 close to E. folleata, which also occurs at the Tortugas. It is 

 probably the descendant of some Epenthesis, and seems to be a 

 newly-arisen species. No studies have as yet been made by 

 zoologists upon the variations of such forms. 



The medusa is highly variable. Out of 1,000 individuals 703 

 are normal radially symmetrical medusae, with five radial canals 

 and five lips at intervals of 72°, while 297 are abnormal in some 

 respect, having 4, 3, 2, or 6, 7, 8 canals or lips. It is remark- 

 able that fully 50% of the abnormal individuals are radially 



