254 PROFESSOR E. RAY LANKESTER. 



relation to the clilorophyll-corpuseles of either green Spon- 

 gilla or greeu Hydra, when in normal conditions. But, on 

 the other hand, an amyloid substance is formed by the green 

 sponge-cell, and stored up in large quantities in vacuoles. 



Equally large quantities of starchy matter are formed by 

 greeuless Spongilla, Accordingly, the Spongilla is not 

 dependent upon chlorophyll for its power of forming amyloid 

 substance. This formation of amyloid substance appears to 

 be due to a synthetical process resident in the colourless 

 protoplasm of the sponge-cell. It is not yet known that 

 the process is a synthesis, or that the decomposition of CO2 

 is connected with it ; but if this could be proved to be the 

 case, we should have strong evidence in favour of the 

 ** screen theory " of chlorophyll. For we should then have 

 the amyloid synthesis going on equally both in green and 

 '' greenless " Spongilla, in the former the protoplasm being 

 protected by chlorophyll from the direct sunlight, in the 

 latter no such protector being required nor developed, and 

 this because the greenless Spongilla exists in deep shade 

 away from the reach of those rays which it is the business 

 of chlorophyll to intercept. 



