320 University of California Publications in Zoologij [Vol. 11 



ered with a layer of the finer brown grains ; this gives the appear- 

 ance of a brown mass, but upon breaking open these globules 

 the red core is always found. These balls are found scattered 

 promiscuously throughout the eye and surrounding tentacle. 

 Plate 15, figure 9, shows an eye-spot in which an u.nusual number 

 of these masses is present. Figure 10 is one of these much en- 

 larged. Although the finer granules of the red pigment are 

 found in the epithelial cells of both eye and tentacle, and even 

 to a smaller extent in the ad.jacent spindle cells, the largest 

 bunches are of too great a size to be contained in any of the 

 type cells of the eye. Some of these appear to be great accumu- 

 lations of pigment granules lying in intercellular spaces, but 

 these are probably enclosed by a distended cell wall, since several 

 of the large ones (though not the largest) were found both in 

 sections and macerations to have a distinct wall and nucleus (pi. 

 15, fig. 11). In composition as well as structure the two pig- 

 ments differ. Although when stained with Delafield's haema- 

 toxylin and eosin little differentiation is .seen, when phospho- 

 tungstic acid haematoxylin or Mallory's connective tissue stain 

 is used the difference become very marked. With the phospho- 

 tungstic the brown remains the same color but the red turns to 

 a yellowish pink. With Mallory's stain the brown still main- 

 tains its natural color, while the red a,ssumes a greenish-blue tint 

 with either the green or the blue predominating. When treated 

 with acids the two pigments behave quite differently. Dilute 

 sulphuric acid dissolves both ; with nitric all the brown seems to 

 be preserved while only the red which is mixed in with the brown 

 is left, a thing which is also true with oxalic acid. Figure 11& 

 shows an isolated epithelial cell which contains no pigment. Both 

 forms of pigment are found in the eyes of the very small forms 

 as well as in those small ocelli of the undeveloped tentacles of 

 adult specimens, but the brown seems to be the dominant type. 



Very little difference was found in the general structure of 

 the of immature animals compared with the adult forms. The 

 number of the cells was necessarily fewer and also smaller in 

 size, but the usual arrangement of epithelial, pigment, and sen- 

 sory cells was the same in both. There seems to be no definite 

 period in the life of Polyorch is when tentacles, with the correlated 



