or in clusters. Each is a sphere with a well marked cell 

 wall anci contains one or two nuclei that stain deeply, and a 

 number of what appear to be chlorophyl bodies. Although these 

 cells have every appearance of being unicellular algae, Keller 

 thinks they are not algae but that they are essential elements 

 of the "mesoderm," for accordirg to his experiments they do 

 not have cellulose in their cell walls. 



There are al^o in certain regions peculiar little vesicles 

 the nature of which is not clear, and which appear in the fresh 

 tissue to be highly refractile granules. There is a nucleus 

 to one side of the vesicle, otherwise it is empty in the pre- 

 served specimens. Accordirg tc Keller, the cell is clear and 

 colorless at the centre while its periphery is thickly filled 

 with minute scales or granules. 



Color Markings . 



The coloring of this semi-transparent animal consists of 

 certain white markings together with shadings of subdued tints 

 of brown, green and blue that are often very beautiful. This 

 is largely due to the last two of the elements in the jelly 

 that I have just described. The green cells give a general 

 greenish brovm color to the entire animal, while the refractile 

 granules produce the white pattern that is so characteristic 

 of this genus and the related Polyclonia. 



- 9 - 



