March 27, 1914] 



SCIENCE 



471 



but probably is not. The apparent increase in 

 rate is more likely due to aggradation with 

 glacial outwash or to the building of a fan on 

 the delta at the northern end. 



Craigton not only began, but probably com- 

 pleted its history as a lake before the tilting 

 occurred; a considerable part of its tilting 

 must have occurred before the Iroquois beaches 

 were tilted and all of it before the Algonquin 

 was tilted, because in the first place its tilting 

 is greater than that of the Iroquois; and in 

 the second, Algonquin tilting did not proceed 

 so far south. Had water remained in Craigton 

 during the tilting, it must have spilled over 

 southward. There can be found no evidence 

 of static water work on the hills above the re- 

 corded beach levels at the southern end. If 

 water stood higher here, then many tracts, 

 low between moraine hills but higher than 960 

 feet, should have been under water and should 

 attest that fact by sorted drift, lake clays, and 

 possibly by black earth deposits of palustrial 

 origin. Nothing of the sort can be found. 



Because the outlet was in the middle portion 

 of the lake the southern part would not be 

 drained by the tilting. Drainage possibly 

 fairly well established would be interfered 

 with; swampy conditions would develop and 

 will persist until more perfect drainage is at- 

 tained. Black, peaty earth, very abundant in 

 the southern part, confirms the belief that this 

 end of the lake was long swampy. In fact 

 artificial ditching has but recently put it into 

 agricultural condition. Hundreds of acres of 

 onions are now grown on the black flats that 

 are sufficiently drained. Water does not stand 

 anywhere on the plain but swampy conditions 

 are not entirely removed. 



George D. Hubbard 



Oberlin College, 

 Oberlin, Ohio 



TBE AMERICAN SOCIETY OF ZOOLOGISTS 

 II 



COMPARATrVE PHYSIOLOQT 



The BeacUons of Normal and Eyeless Amphibian 



Larvm to Light: Henby Laurens. 



Although the photic reactions of Amphibians 

 have been extensively investigated very little has 



been done on the larval forms. The purpose of the 

 present investigation was to test the reactions to 

 white light of normal and eyeless frog (i?. pipiens 

 and S. sylvatica) and Amblystoma (A. punctatum) 

 larvffi. The optic vesicles were removed from the 

 blinded individuals at a stage of development soon 

 after the closure of the neural folds, when the tail 

 bud is just beginning to be perceptible. Frog 

 larvae, both normal and blinded, show no reaction 

 to the stimulus of light. Both normal and eyeless 

 Amblystoma larvee, however, show a very decided 

 positive phototasis. The reactions of the blinded 

 individuals are apparently not due to the direct 

 stimulation of the central nervous system by the 

 light as is shown by a series of experiments in 

 which three small areas of the larvfB were illumi- 

 nated, these areas being roughly the head-region, 

 the ventre -lateral mid-body region, and the tail- 

 region. Positive responses were obtained when 

 each of these regions were illuminated by a nar- 

 row beam of light, the percentage of positive re- 

 sponses being practically the same in each case. 

 The skin ehromatophores of Amblystoma larvae 

 show different conditions of expansion and con- 

 traction of their pigment under different condi- 

 tions of light and darkness; the conditions in the 

 normal and blinded larva; being exactly opposite. 

 Normal larvse placed in diffuse light are pale 

 (light brown), blinded larvas so placed are very 

 dark. Normal larvEe placed in darkness are darkly 

 pigmented (dark brown), while blinded larvae so 

 placed are very pale. But normal larvae placed in 

 diffuse light on a black background are darkly pig- 

 mented, thereby showing the effect of the back- 

 ground. These different conditions of the pigment 

 in the skin ehromatophores do not affect the sensi- 

 tiveness of the larvae to light, but previous ex- 

 posure to light or adaptation to darkness do, in 

 that dark-adapted larvae are more sensitive to light 

 than are those which have been kept in the light. 



An Analysis of the Egg Extractives of Arbacia 



and Asterias: Otto C. Glaseb. 



Analyses (1) by means of sperm-suspensions; 

 (2) by means of qualitative chemical tests; (3) 

 by means of the rate of development, were made. 

 The results briefly summarized, are: 



1. A general corroboration of F. E. Lillie 's ob- 

 servations with respect to Arbacia punctulata; 

 their extension in certain directions, and their ap- 

 plication to Asterias forbesii. Hetero-agglutina- 

 tion and hetero-activation between Asterias and 

 Arbacia were found. Agglutination is very likely 

 the result of a surface effect. 



