July 18, 1913] 



SCIENCE 



99 



Jennings sought an explanation of behavior 

 based on physiological grounds and concluded 

 that since the organism may react differently 

 under apparently similar conditions, reactions 

 are due to differences in physiological states. 

 He cites instances in which the physiological 

 conditions, such as hunger, for example, are 

 known to modify reactions. 



Mast (1911, page 369) admits that the " be- 

 lief that light in some way influences the 

 activity of organisms by chemical changes 

 which it causes in them" is founded on hy- 

 pothetical assumptions. Any direct evidence 

 either in agreement with or opposed to these 

 views, although it may need further verifica- 

 tion, would be of importance. 



It must be remembered that little is posi- 

 tively known concerning the character of 

 chemical changes in metabolic processes. It 

 is true, however, that of the various physiolog- 

 ical states, or conditions which might effect 

 them, the maintenance of the neutral or 

 slightly alkaline condition in an organism is 

 of the greatest importance, and this condition 

 is not easily changed. Any change in this 

 state it should be possible to detect provided 

 a proper means be found. It is assumed 

 that the organization of protoplasm involves 

 and demands physical-chemical relations and 

 changes of a progressive kind, with some 

 range of disturbance possible without causing 

 complete disorganization or breaking down of 

 the chain of changes. These changes must be 

 maintained within the limits of the conditions 

 which make possible their continued recur- 

 rence. This has aptly been likened to a 

 " vortex." 



The natural result of a stimulus breaking 

 in upon these regular changes may be to stop 

 some, accelerate others, divert others into com- 

 binations different from those which would 

 normally occur. That the stimulus (light) 

 would cause a chemical change which would 

 be the cause of the reaction is limiting the 

 possibilities. From the viewpoint of the 

 physiological processes it becomes a matter of 

 importance to discover the nature of these 

 disturbances. As previously stated, an acid or 

 alkaline condition is of primary significance. 



the right condition being maintained through 

 the interaction of certain basic and acid sub- 

 stances present. If it is not possible to detect 

 these conditions directly it might still be pos- 

 sible to discover variations in the amount of 

 elimination of products or alteration in their 

 character. Accordingly, an attempt was made 

 to discover any possible difference in these 

 conditions. 



To test for differences in respiration in the 

 starfish two methods were used. In one series 

 of experiments an indicator for carbon dioxide 

 was introduced into the given amount of sea 

 water with the specimen to be tested. Parallel 

 experiments, one in the shade and one in the 

 sunlight and one control, were compared. In 

 a second series specimens were exposed in the 

 shade and the sunlight in equal amounts of 

 tested sea water, the sea water then after 

 equal intervals of time being again tested. 



Having made use of neutral red in class ob- 

 servation on the reaction of protoplasm and 

 vacuoles in Parammcia, this was tried in the 

 starfish. Furthermore, neutral red might also 

 show differences in intra vitam staining in 

 light and shade. Dilute sokitions of neutral 

 red were made in sea water which is normally 

 slightly alkaline in reaction, from 1 : 10,000 to 

 1 : 60,000. A more dilute solution was used in 

 some cases. Given amounts, 200 c.c. to 400 c.c. 

 of the same solution were placed in each of 

 three large clean finger-bowls. One of these 

 was kept for control. Two starfish equal in 

 weight and as nearly alike as it is possible to 

 select, which were found to react normally to 

 light were placed one in each of the other two 

 vessels. One of these vessels was then placed 

 in the sunlight and the other in the shade. 

 Both vessels were placed in a shallow aquarium 

 of fresh sea water in order to maintain equal- 

 ity of temperature 18° centigrade. At inter- 

 vals of two or five minutes a careful compari- 

 son was made to note possible changes in ac- 

 tivity and degree of staining shown by each 

 specimen. In practically every experiment at 

 the end of five minutes, solutions and speci- 

 mens showed distinct differences. In the ves- 

 sel in the shade the solution showed a charac- 

 teristic acid reaction, while at the same time 



