in] GREEN CELLS OF CONVOLUTA 89 



In the second place, when examined immediately 

 after capture, the transparent reticulum of the cells 

 (Fig. 18, n) is found to contain colourless, refractive 

 globules or droplets, which, when treated with suit- 

 able reagents (osmic acid, etc.), may be recognised to 

 consist of, or at all events to contain, fat. Now, it 

 is well known that certain plants, some algse among 

 others, store their reserve, photosynthesised carbon- 

 compounds, not as starch, but as oil. That these 

 globules are of the nature of reserve substances 

 derived from the products of photosynthetic activity 

 is rendered probable by the following facts. First, 

 when a catch of animals is divided into two lots, and 

 one is kept in darkness and the other in the light, the 

 reserve fat-globules disappear more quickly from the 

 yellow-brown cells of the dark-kept animals than 

 from those of the animals kept in the light. Second, 

 if two similar batches of animals are kept in darkness, 

 one in pure (filtered) sea-water, the other in sea-water 

 containing sea- weed from the C. paradoxa zone, fat 

 disappears from both, but more quickly from the 

 yellow-brown cells of the starved animals. If the 

 fat were derived from the food (sea-weed with its 

 micro-flora and fauna) there would seem to be no 

 reason why it should disappear at all from the yellow- 

 brown cells of the fed animals. On the other hand, 

 assuming that the fat-globules serve as food-material, 

 not only for the yellow-brown cells but also for those 



