]38 JOURNAL OF THE [December, 



green slime of our ponds, are chiefly composed. But when we 

 come to the higher algae, the so-called seaweeds, though some 

 of these are green, the green ones are in the minority. Some 

 are black, some are purple. Others are olive-colored, but the 

 most beautiful are red. Hence, the word chlorophyl, applica- 

 ble to the green substance only, was supplemented by the word 

 endochrome, which indicates this substance in all its colors ex- 

 cept green. Thus, so much of the protoplasm as is elaborated 

 into this yellowish substance in the diatom, we call endochrome. 

 In recent vegetable chemistry the coloring matter in each of the 

 lower orders of plant life is regarded as a principle and has its 

 chemical name. For example, the yellow-brown pigment 

 in the diatom is called diatomine, and similarly of the rest. 

 It is highly probable that this diatomine is chiefly iron with a 

 little chlorophyl ; and that in some modified way chlorophyl, or 

 leaf-green, as a protoplasmic form of nitrogen, is present to a 

 greater or less extent in all of these plant substances. In them. 

 Prof. H. L. Smith showed by spectrum analysis, long ago, indi- 

 cations of both chlorophyl and cellulose. So the little diatom, 

 besides stocking its house with endochrome, eliminates and 

 elaborates from the water, cellulose, silica, and iron. It also 

 adjusts and fixes each particle of its coloring contents one by 

 one in place, as does the artist in mosaic arrange the variously 

 colored patterns of his work. Within the endochrome is a 

 central spot which we may call the nucleus, around which ap- 

 pears a ring of dots, chromic-iron granules, each of which be- 

 gins a line of unconnected dots or granules that reaches to the 

 outer boundaries of the endochrome. And shall we doubt that 

 within this diatom-cell the beautiful phenomenon of life-force, 

 circulation, cyclosis, is active ? Some students of these tiny 

 forms think that they have observed it. 



Fourth. How does the diatom feed ? How take in its pabu- 

 lum ? How it lays down or secretes the silica is conceivable, 

 for we may regard it as an infiltration upon a pattern ; but 

 whence the beautiful pattern, who can tell ? And by what vital 

 alchemy does it take from the water the constituents of its en- 

 dochrome of amber, of its walls of glass, and of its protecting 

 membrane of pellucid keratose ? No one knows. But how it 

 takes in its unelaborated pabulum, how the closed box permits 

 food to enter, is a process which perhaps we can explain. Let 



