TESTS OF CHLOROPHYLL. 73 



various. Mr. Sorby has shown that the green variety, or 

 species, of our common fresh-water sponge (SpongiUa fluviatilis) 

 owes its colour to minute particles of colouring matter which 

 seemed to be identical with chlorophyll, for he proved that their 

 spectra were identical. The same method was followed by Mr. 

 Ray Linkester, who, with regard to Spongilla, came, it is true, to 

 a conclusion different from that of Mr. Sorby, but, on the other 

 hand, recognised the presence of chlorophyll in Hydra viridis. 

 The much-lamented Max Sigismund Schultze, to whom we owe 

 the earliest accurate observations on animal chlorophyll, endea- 

 voured to prove its identity with vegetable chlorophyll by com- 

 paring the chemical reactions of various solutions of each, as 

 well as by observing that Vortex viridis loses its colour in the 

 dark, and that the animal, exactly like plants, always seeks 

 the lightest side of the aquarium. But the decomposition of 

 carbonic acid by animal chlorophyll has never been demon- 

 strated, although Sorby himself has pointed out that it would 

 be very interesting to know whether such a process does 

 actually take place in animals that contain chlorophyll ; for if 

 the decomposition of carbonic acid could be ascertained in 

 these low forms of animals it would prove that they are able to 

 elaborate and assimilate organic matters in the same way as 

 plants, though they also, like all other animals, require ready 

 elaborated organic nourishment, or they cannot thrive. But 

 this would be a fact of very far-reaching significance, exhibiting 

 a certain affinity to the instances known to us of carnivorous 

 or insect-eating plants (Drosera, Diona?a, and others). 



At the same time it must be pointed out, on the other hand, 

 that granting unconditionally that the pigment of the animals 

 that appear to contain chlorophyll is truly of the nature of 

 chlorophyll its presence in animals may be explained in two 

 different ways. In the first place, if the chlorophyll bodies of a 

 Stentor, for instance, were really elements of the animal tissue, 

 elaborated from its protoplasm by the direct influence of light, 

 then but only then might we say that there were actually 

 animals which assimilate in the same way as plants. But, in 

 the second place, it might be possible that the green constituents 

 were not integral elements of the animal, but foreign bodies 



