98 



SCIENCE 



[N. 8. Vol. XXXVIII. No. i 



Since the New York soil contained only- 

 living organisms of B. radicicola known to be 

 capable of inoculating alfalfa, the inoculation 

 of alfalfa by the organism isolated from the 

 New York soil was to be expected. 



It seems fair to conclude that B. radicicola 

 grows but sparingly and shows no especial 

 characteristics upon synthetic agar made in 

 accordance with the formula reported by 

 Grieg-Smith, which seems to be no more selec- 

 tive than the synthetic agar we have employed 

 for many years in the Washington labora- 

 tories, and is perhaps less selective than the 

 congo-red agar described by one of us.' Fur- 

 ther development of technique or of culture 

 media will be required before we may hope to 

 secure reliable data regarding the relative dis- 

 tribution and quantitative function of B. 

 radicicola in the soil. 



"Karl F. Kellerman 

 L. T. Leonard 



BDEEA0 or Plant Industry, 

 "Washington, D. C. 



some effects op sunlight on the starfish 



Starfish have been much studied for their 

 reactions to light. Their general reactions 

 and behavior have been well described by 

 Preyer, von Uexkull, Jennings and others, and 

 there is general agreement in the results re- 

 corded by these writers. Details of behavior 

 of the different parts affected by light axe for 

 the most part meager or omitted. 



The general reactions of Asterias forhesii 

 are essentially like those described for other 

 starfish and there is no reason to suppose that 

 its reactions are essentially diiierent in detail 

 so far as it is possible to observe them. It 

 has been previously shown by the writer' that 

 certain parts of the animal are sensitive to 

 light. It has further been found that there is 

 a definite time reaction between the moment 

 when the light strikes the sensitive parts and 



"KellermaB, Karl F., "The Eelation of Crown- 

 gall to Legume Inoculation," U. S. Department 

 of Agriculture, Bureau of Plant Industry, Circular 

 76, p. 4, 1911. 



' Science, K. S., Vol. 35, p. 119. 



the moment when they show a definite visible 

 response, and the general reaction which fol- 

 lows, provided the light has sufficient in- 

 tensity. 



Individuals without the pigment or " eye " 

 spots react as definitely to light as do those 

 with the pigment spots intact. This was also 

 found to be true for Echinaster (Cowles). 

 The upper surface, the sides of the rays, the 

 ventral surface and the tube feet are sensitive 

 to light, since they show a direct response to 

 it. The dermal branchia also show response 

 to light stimuli. The behavior of dermal 

 branchia is of peculiar interest, since their 

 retraction must influence the extent of the 

 aerating surface of the animal. The sudden 

 illumination of a ray or a spot on it causes a 

 retraction of the parts illuminated. If the 

 area is large there is a bending of the ray ven- 

 tralward no matter what the direction of the 

 source of light. Following this primary re- 

 flex, there arise movements which lead even- 

 tually to the general response or behavior. 

 Three stages are recognizable. These are: 

 the initial or direct effect of light; the local 

 direct response of the parts affected, and lastly 

 the general eifect and reactions in response to 

 the influence of the preceding changes. It is 

 apparently through these interactions that the 

 external stimulus is finally transformed into 

 reaction and behavior through the vortex of 

 metabolic changes in protoplasm. 



Loeb has maintained that " reactions are 

 caused by a chemical effect of light " and that 

 " the velocity or the character of the chemical 

 reactions in the photosensitive elements of 

 both sides of the body is diiierent," and hence 

 " the muscles or the contractile elements on 

 one side of the organism are in a higher state 

 of tension than their antagonists." One 

 wishes for more direct evidence and, if such is 

 possible, direct proof that light does influence 

 the chemical processes of normal metabolism, 

 than the above assumptions afford. While it 

 is generally assumed that light does cause 

 chemical changes in organisms and these must 

 influence the reactions of the organisms, there 

 is a significant absence of direct experimental 

 proof. 



