436 NOTES AND MEMOKANDA. 



Geddes gives important observations referable to our sixth 

 category, from which it appears that the green substance of 

 Convoluta does not exist in the form of grains, nor of fine 

 granules, but "is diffused throughout the whole protoplasm" 

 of certain cells, which lie beneath the circular and longitu- 

 dinal muscles. Thus, the green substance of Convoluta differs 

 most markedly from that of the allied Vortex viridis, in which 

 it occurs in the form of drops in the cells ; equally it differs 

 from that of Hydra viridis and of Spongilla, which occurs 

 in the form of grains embedded in the protoplasm of cells, 

 the grains having the form of concavo-convex discs in Spon- 

 gilla. In Bonellia, too, and Cheetopterus the green substance 

 is granular j in Idotea it is diffused. Nevertheless, Mr. 

 Geddes obtained evidence of the formation of fine granules 

 of starch in the green cells of Convoluta by the application 

 of iodine to fresh-teased preparations of the worm's tissues. 

 This we must regard as the most important part of the evi- 

 dence which he is able to adduce in favour of the view that 

 Convoluta SchidtzU is actually nourished by the activity of 

 its chlorophyll — that it, in fact, feeds on carbonic-acid as a 

 green plant does. 



It remains to be seen whether similar or even more con- 

 clusive evidence of this kind can be obtained from the 

 examination of such chlorophyllaceous animals as Hydra and 

 Spongilla. 



Mr. Sorby, writing in 18T5 in this Journal on Spongilla, 

 said : "It would, I think, be well worthy of study to ascer- 

 tain whether low animal forms which, like Spongilla, contain 

 chlorophyll, have, when exposed to light, the power of de- 

 composing carbonic acid, and supporting themselves, to some 

 extent, as plants .... If so, they would be animals to some 

 extent capable of plant- like growth, and would thus be the 

 reverse of those plants which have lately attracted so much 

 attention on account of their being able to partially support 

 themselves by means of complex animal food, which they can 

 digest and absorb like the most perfect classes of animals." 

 Mr. Geddes's researches have established, in one case at 

 least, what the mere fact of the presence of chlorophyll in 

 animals had led naturalists to entertain as hypothesis. He 

 remarks : " As the Drosera, Dionsea, &c., which have 

 attracted so much attention of late years, have received the 

 striking name of carnivorous plants, these Planarians may 

 not unfairly be called vegetating animals, for the one is the 

 precise reciprocal of the other. Not only "does the Dionaea 

 imitate the carnivorous animal, and the Convoluta the ordi- 

 nary green plant, but each tends to lose its own normal 



