Cytology and Movements of the Cyanophycea. 291 



crust to function as a chromatophore, though not exactly 

 deserving that name, while Hieronymus considered this 

 crust not only to function as such, but to be rightly so called. 

 Chodat was unable to distinguish between central body and 

 crust layer and consequently, with Deinega, considered that 

 no special color-bearing organ was present. Zul<al defined 

 the chromatophore as any "portion of protoplasm which 

 contained the coloring pigment." In general this seems to 

 be a proper definition, though in its broad sense it would 

 include the whole of the cytoplasm. In the Cyanophyceae 

 which serve for the basis of this investigation, the two pig- 

 ments, chlorophyll and phycocyan, are dissolved in the outer 

 protoplasmic zone of the cell, coloring the greater portion 

 of it. Surrounding this zone is a delicate colorless proto- 

 plasmic layer separating it from the cell wall. The colored 

 zone has no definite structure other than that of the pro- 

 toplasm and the cyanophycin granules which it contains. 

 In the sense of Zukal's definition, then, the colored zone 

 would rightfully be termed a chromatophore, and it cer- 

 tainly functions as such, though it also has to perform the 

 functions of the cell cytoplasm as well. This is not to be 

 wondered at, for in primitive organisms like these, one 

 would expect to find an overlapping of functions which will 

 later be differentiated and performed by separate organs. 



Hegler (38) brought together in tabular form the views 

 generally held concerning the form which the coloring mat- 

 ter takes. It is here reproduced with a few additions. 



I. — Pigment completely diffused in the protoplasm; Nae- 

 geli, Schmitz, Zacharias and the text-books. 



II. — Pigment embedded within the walls of a web struc- 

 ture of the crust layer; Palla and Biitschli. 



III. — Pigment in net-like plates surrounding the central 

 body ; Deinega. 



IV. — Green chlorophyll in grains, embedded in a color- 

 less fibrillar system; according to ]\Ieyer, moreover, the 

 grains correspond to the chlorophyll bodies of higher plants 



