8i 4 THE POPULAR SCIENCE MONTHLY. 



up of several simpler compounds not well understood. Nor is it always 

 green, though in that form it occurs most familiarly. Sometimes the 

 true chlorophyl is obscured by some other color, and is nevertheless 

 perfectly functional, physiologically speaking ; for instance, a yellow 

 color is particularly common in the lower forms of plants as in 

 the algse. 



In 1871 Cienkowski boldly announced his conviction that certain 

 yellow cells, which, first pointed out by Huxley, had for some time 

 attracted attention in the substance of radiolarians, were really no part 

 of the animals themselves, but rather veritable algve living in the ani- 

 mals. Haeckel had previously called them " liver-cells," and when 

 starch was found in them he believed his view confirmed, as it is in the 

 liver of the higher animals that glycogen a form of starch is con- 

 stantly present. The views of Cienkowski made little progress, how- 

 ever, till 1879, when a distinguished morphologist, R. Hertwig, of Jena, 

 who had previously taken sides with Haeckel, adduced reasons which 

 inclined him to the belief that the yellow cells were " parasitic," as 

 Cienkowski had considered them to be. 



In the same year (1879) the brothers Hertwig concluded that the 

 so-called pigment-bodies in the tentacles of certain sea-anemones are 

 true alga? plants, multiplying by tranverse division. Then followed 

 quickly the paper by Dr. Brandt, referred to at the beginning of this 

 review. His work was extensive, and resulted in a complete confirma- 

 tion of the observations of Cienkowski and the Hertwigs. He fully 

 believes that the yellow cells are true algae, and was able to prove his 

 points to his own satisfaction. He went, however, a step further, and 

 announced his conviction that all animal chlorophyl is to be consid- 

 ered as located in associated vegetable organisms, which, together with 

 the animal, make up " a partnership of plant and animal life." He un- 

 hesitatingly puts Hydra viridis and Spongilla (green variety) in this 

 position, and thus disposes of all " vegetating animals," or animals liv- 

 ing like plants endowed with chlorophyl. 



In October, 1881, Mr. Geddes visited Naples for the sake of mak- 

 ing further studies upon this subject, and in the paper in " Nature," 

 referred to above (and which has been freely drawn upon in preparing 

 this review), he gives a summary account of his work. 



He devoted his attention at first to the yellow cells of Radiolaria, 

 and was completely successful in demonstrating in them not only a 

 cell-wall of cellulose and contents made up of protoplasm and nucleus, 

 but he was also able to watch their growth both before and after the 

 death of the animal ; and, what was of special interest, he obtained a 

 fair amount of evidence that certain tiny bubbles which in sunlight 

 studded the radiolarians were really made up, in part at any rate, of 

 oxygen. Besides this, he pronounces starch to be invariably present, 

 and completely confirms the observations of Cienkowski and Brandt 

 as to the survival and growth of the yellow cells long after the animal 



