292 Phillips on a Comparative Study of the 



and the blue pigment diffused in the cell sap ; Hieronymus 

 and Meyer. 



V. — The blue and green pigments both in the same very 

 minute granules, which are themselves embedded in, and 

 connected by, a protoplasmic thread with each other and 

 with a hyaline-like layer of peripheral protoplasm on the 

 outer side and with a protoplasmic pellicle, or pocket, sur- 

 rounding the central bodies, much as the nucleus of Spiro- 

 gyra is surrounded ; Hegler. 



In higher plants the chromatophores appear to be seg- 

 mented off from the nucleus. They seem to require some 

 nuclear constituent before they are able to perform their 

 function. It is not improbable that there may be some 

 nucleoplasm in the outer zone of the Cyanophyceje which has 

 not yet been aggregated into definite forms as in the higher 

 plants, and its function, together with that of the coloring 

 matter, not yet divorced from the functions of the cyto- 

 plasm. Indeed this would be suggested by the fact that the 

 peripheral protoplasm retains a very diffused coloring with 

 Heidenhein's iron-ammonia-alum hematoxylin and other 

 nuclear stains. TJiis quite strongly differentiates it from 

 the delicate surrounding colorless layer of ectoplasm which 

 lines the cell wall. Such diffused staining is increased or 

 diminished according to the composition of the culture fluid, 

 as explained below for the chromatin of the central body. 



The Granules. 



Besides the chromatin vesicles of the central body which 

 have already been discussed, two other forms of granules 

 may be found in the outer protoplasmic zone of the Cyano- 

 phyces. Of these, the most common are the cyanophycin 

 granules which permeate the greater portion of the periph- 

 eral zone, especially the outer portion of it just under the 

 thin ectoplasmic layer mentioned above. These granules 

 are variable in number, being more numerous in plants 



