COLOR VISION 355 



of the authors mentioned above is as thorough as that 

 of Lubbock. And since it leads to no essentially new or 

 contradictory conclusions, with the exception of that of 

 Bethe, it would be of but little value to review it here. 

 That of Minkiewicz is nevertheless somewhat out of the 

 ordinary, and it may consequently not be out of place to 

 devote a few paragraphs to it. 



/ 



3. Higher Crustacea — Experiments of Minkiewicz 



Before presenting the work of Minkiewicz on the Crus- 

 tacea, it will be necessary to refer briefly to his earlier obser- 

 vations on the nemertean Lineus ruber, since these form 

 the basis of his later work. 



Minkiewicz exposed these worms in horizontal beams 

 of light of different colors produced by means of a prism, 

 colored glass or tissue paper. Under normal conditions 

 they were found to be negative in blue or green and positive 

 in red or yellow. But if left for several hours in 100 c.c. 

 of sea water diluted with 25 to 80 c.c. of distilled water, 

 they became positive to the more refrangible rays of the 

 spectrum. The striking peculiarity of these reactions is 

 that in colorless light the organisms wxre negative under 

 all conditions. He says (1907, p. 48): '' I have not as yet 

 found, in spite of long continued researches, a single means 

 of transforming the negative phototropism of Lineus into 

 positive phototropism by agents either chemical, osmotic 

 or thermic. Thus, for example, the animal remains nega- 

 tive until its death in the presence of white light whatever 

 the concentration of the sea water." 



The author concludes that all the chromatic rays have a 

 specific action independent of each other and of white light. 



Among the Crustacea, Minkiewicz experimented with 

 spider crabs and hermit crabs. His studies on the former 

 were devoted primarily to Maja verrucosa and Maja squi- 

 nado, but he claims to have made analogous observations 

 on different species of Pisa, Inachus and Stenorynchus. 



