376 P. W. GAMBLE AND FIJEDERICK KEEBLE. 



small, and infers that these green cells coutiuually contribute 

 the major part of the photosynthetic process to the animal; 

 but as a matter of fact the poverty of starch must have been 

 due to poorness of condition, for, in their natural state, Con- 

 voluta always give an intense blue iodine reaction. 



We have examined the effect of different rays of the 

 spectrum upon the manufacture of starch by the use of 

 coloured screens placed over animals kept so long in the 

 dark as to be free from starch. We find that when such 

 depleted animals are exposed to light, starch makes its 

 appearance in less than ten minutes in bright sunlight, and 

 that it may be recognised in animals kept beneath screens 

 transmitting red and blue light, but not in animals kept 

 beneath green screens. The appendix and its explanation 

 (p. 377) give the details of the experiment, the main result 

 of which was the following : 



After six hours' exposure, the Convoluta beneath the 

 red screen, transmitting a band of red light from B to a 

 little beyond C (Fraunhofer lines), showed plenty of starch. 

 The Convoluta beneath the blue screen (which transmits a 

 little green light and all the blue) showed a fair amount of 

 starch. Those beneath the green screen (which transmits 

 all the green and a narrow band of extreme red beyond 

 Fraunhofer line B) showed no starch. Naturally this method 

 does not measure the amount of assimilation, but only exhibits 

 the amount of photosynthesised material stored as starch. 

 Yet the results show strikingly that the relative iuHueuces of 

 monochromatic light on photosynthesis of the green cells of 

 Convoluta are similar to their action on assimilation in 

 ordinary green plants. The maximum assimilation, as indicated 

 by the maximum storage of starch, coincides in both with the 

 light between B and C of the spectrum (A 600 — 680). A second 

 maximum, singularly well marked in Convoluta, and also 

 known to exist in the case of green plants, occurs in the 

 blue. A point worthy of note is the non-ap])earancc of 

 starch in Convoluta under green light. In ordinary green 

 plants green is the region where photosynthesis is the least 



