784 



SCIENCE 



[N. S. Vol,. XXV. No. 646 



of Sea-water Solutions of Magnesium 

 Chlorid: Chaeles R. Stockaed, Colum- 

 bia University. 



Fundulus embryos when developed in 

 certain strength solutions of MgCl, in sea- 

 water form a large single median eye. 

 This condition is comparable to the one 

 eyed human monsters known as Cyclops, 

 Cyclopia or Synophthalmia. 



The single eye results from an antero- 

 medio-ventral fusion of the elements of the 

 two optic vesicles at an early develop- 

 mental stage. This fusion is more or less 

 complete in the different embryos. 



The large compound optic cup induces 

 the formation of a single lens. This lens 

 is formed from ectoderm different in posi- 

 tion from that of the normal lens-forming 

 region. The lens is abnormally large in 

 size aa is also the optic cup, and the size 

 of the former varies directly with that of 

 the latter. It is probable that there is no 

 localization of lens-forming substance in 

 the ectoderm of the fish embryo. This 

 inter-relationship in the development of 

 the optic cup and lens is interestingly com- 

 pared with the processes of development 

 in the amphibian eye as shown by recent 

 experiments. 



Mixed sea-water solutions of MgClj and 

 NaCl also cause the one-eyed condition. 

 Since such a defect is characteristic of the 

 MgClj action when used in sea-water solu- 

 tions one must infer that the Mg constitu- 

 ent in the mixture is responsible for the 

 result. 



Method of Making Series of Anatomical 

 Dramngs: G. A. Drew, University of 

 Maine. 



The Influence of Direction vs. Intensity of 

 Light in Determini7ig the Phototropic 

 Bespo^ises of Organisms: Leon J. Cole, 

 Kingston, R. I. 

 The large land planarian, Bipalium 



kewense, was the principal animal experi- 



mented with. Its responses were first tried 

 to shadows from a light directly overhead, 

 i. e., non-directive. It was then tested in a 

 partial shadow, a strip of less intense light 

 in an area of more intense illumination. 

 In this case all the light came fr.om one 

 direction, namely, horizontally, from one 

 side. Although strongly negative, the 

 worms would crawl directly toward the 

 light in the partial shadow rather than 

 turn out into the greater intensity. A 

 similar result was obtained with the earth- 

 worm (Allolohophora fcetida). In these 

 experiments Bipalium and Allolobo-phora 

 appeared to respond to intensity alone, re- 

 gardless of the direction of the impinging 

 light. 



Chromatin Changes in Hydroids: W. M. 

 Smallwood, Syracuse University. 



The Sexual Phase of the Life Cycle in 

 Amoeba: M. M. Metcalp, Oberlin Col- 

 lege. 



The Existence of an Organ of Equiliira- 

 tion in Certain of the Lower Crustacea: 

 C. 0. EsTERLT, Harvard University. 

 (Introduced by E. L. Mark.) 



The Habits and Life History of Crypto- 



branchus allegheniensis : Bertram G. 



Smith. (Introduced by Dr. 0. C. 



Glaser. ) 



The adult dyptohranchus has its dwell- 

 ing place in a cavity or cavern under a 

 large rock, in swift and shallow water. 

 The animal seldom comes out during the 

 daytime, except during the breeding sea- 

 son. The eggs are laid and fertilized dur- 

 ing the first two weeks in September. 

 They are deposited in the usual dwelling- 

 place of the animal. About 450 eggs are 

 laid by a single female. Fertilization is 

 external as in fishes ; no spermatophores are 

 formed. After the eggs are deposited they 

 are usually guarded for a time by the male, 

 who fights and drives away other hell- 



