CHLOROPHYIyL-CORPUSCLES AND AMYLOID DEPOSITS. 243 



relation to the formation of the winter "gemmules," and 

 the providing them with a store of food material. 



Angular corpuscles of colourless Spongilla. — The fact that 

 Spongilla Jluviatilis occurs almost as frequently in a colour- 

 less or rather pale salmon-coloured state as in the green 

 state, is one of very great importance in relation to the 

 nature and history of the chlorophyll-corpuscles found in 

 the latter form. Whenever Spongilla grows with deficient 

 access of sunlight it does not develop a green colour, but it 

 appears to be none the less vigorous. I have seen enor- 

 mous growths (many pounds weight) of colourless Spongilla 

 on the lower surface of a barge removed from the river at 

 Oxford. Frequently also in the locks on the Thames, 

 sheet-like growths of Spongilla are seen which are only 

 mottled with green, their colour being in other parts light 

 brown. 



This fact, at first sight, seems to tell in favour of the 

 theory that the chlorophyll- corpuscles are parasitic or- 

 ganisms, which can only attack and thrive in such growths 

 of Spongilla as are exposed to direct sun light. 



An examination of the colourless specimens of Spongilla 

 with the microscope at once, gives a very different significance 

 to the facts. In the amoeboid cells of the colourless Spongilla 

 it is true that no green-coloured corpuscles can be found, 

 hut colourless corpuscles are present, which appear to be the 

 same bodies as the chlorophyll-corpuscles in a modified con- 

 dition. These are angular irregular corpuscles of the same 

 average diameter as the chlorophyll-corpuscles (figs. 6, 11, 14, 

 PI. XX), and occurring in the same abundance. If cells be 

 taken from a piece of sponge of a /?aZ<? green colour, which 

 is, so to speak, becoming green, individual cases may be 

 observed in which there are one or two chlorophyll-corpus- 

 cles present amongst the angular colourless corpuscles. In 

 such specimens too colourless corpuscles may be detected, 

 which assume the concavo-convex shape of the normal 

 chlorophyll-corpuscles (fig. 7). 



It is difficult to avoid the conclusion that the colourless 

 angular corpuscles are capable of either directly developing 

 into chlorophyll-corpuscles under the influence of sunlight, 

 or that in the process of their development they can be so 

 modified by the influence of sunlight as to become, instead 

 of angular colourless corpuscles, concavo-convex chlorophyll- 

 corpuscles. 



An important fact in this connection, which I think goes 

 far to prove that the chlorophyll-corpuscles of Spongilla are 

 formed by the protoplasm of the sponge-cell, was published by 



