BEHAVIOR OF LOWER INVERTEBRATES 379 



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is in the blue at X? 4735 A. u. This is approximately the same 



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region found by Blaauw for seedlings of Avena, viz., X? 4780 A. u. 

 The regions in red, orange, and yellow, it is maintained, have 

 practically no effect on either Avena or Eudendrium. Loeb 

 and Wasteneys conclude that, " The heliotropism of the sessile 

 animal Eudendrium and that of the sessile plant Avena are there- 

 fore identical even as regards the most efficient wave length." 

 These authors (26) in another article, conclude that in plants 

 as well as in animals " There seem to exist two types of helio- 

 tropic substances, one with a maximum of sensitiveness (or 

 absorption) in the yellowish green (near X= 534 /a/a) and the 

 second with a maximum of sensitiveness in the blue (near X = 

 477 ma 1 )." According to them the distribution of these two 

 photosensitive substances is without reference to the systematic 

 boundaries of the two groups. 



Mast (27), in studying the relative stimulating efficiency of 

 spectral colors for fifteen species of organisms finds that with 

 the exception of two forms they fall into two groups. In the 

 first group, viz., Pandorina, Eudorina and Spondylomorum, the 

 region of stimulation begins in the blue between 430 and 440 /a/a 

 and ends in the red at about 640 /a/a, the maximum being in the 

 green between 530 and 540 pp. In the second group, viz., 

 Trachelomonas, Phacus, Euglena (five species), Gonium, Areni- 

 cola larvae, and earthworms, the region of stimulation begins 

 in the violet between 420 and 430 /a/a and ends in the green near 

 520 /a/a; the maximum being in the blue between 480 and 490 /a/a. 

 The author also finds that the maximum region of stimulation for 

 Chlamydomonas is in the green very near 510 /a/a and for the blow 

 fly larvae approximately at 520 /a/a. No difference in the rela- 

 tive efficiency of these different regions was found for a given 

 species either when it was tested under different conditions of 

 illumination and temperature, or when the organism reacted 

 negatively or positively. 



Paul (28) points out that decapods, because of their hard integ- 

 ument and peculiar vascular system, run great risk from hemor- 

 rhage in the injury of one or more of their appendages. He 

 then shows how this is guarded against by self-amputation and 

 makes a very careful study of the processes involved in this act 

 and later regeneration. " Valvular action of the diaphragm at 

 the breaking plane plays a greater part in stopping of hemorrhage 



