40 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



When first observed this individual presented an appearance like that shown 

 in figure 76, with the pigment in scattered granules. In a short time a change 

 began to take place, the pigment moving slowly into the region of the girdle 

 and collecting into a wide mass or band which extended some distance on both 

 sides of the girdle (pi. 7, fig. 82) . Though normally pigment occupies a position 

 close to the periphery of the body, yet this band formation took place inside 

 of the girdle without extending into the lips of the girdle, which were clear. 

 The remainder of the cytoplasm was apparently free from ijigment also. Soon 

 after this formation was completed further changes began. Small nodules ap- 

 peared along the margin of the band, like outpushings from the main mass. 

 These were pinched otf and began to move out into the cAi:oplasm. This process 

 continued until the entire band had become dissipated, the granules moving 

 away until at the end of the period of observation the individual again presented 

 the same appearance as when first noted (pi. 7, fig. 76). 



Indications of this same motility of the piginent are to be seen in the red 

 pigment in G/jrodiuiion coralliunm (pi. 10, fig. 117). The position of this in 

 the cytoplasm varies greatly in different individuals as well as in successive 

 pei-iods of time in the same specimen. One peculiarity of the movement of 

 coloring matter or piginent in species which have a striate surface may be ob- 

 served in this form. This is the marked tendency of such material to follow^ 

 the lines of striae on the surface, where it may collect in small granules or 

 become massed in long bands. Gyrodinium fulvum (pi. 7, fig. 70) and more 

 strikingly, G. virgatum (pi. 10, fig. 112), exhibit this same peculiarity. 



Another marked feature of the behavior of pigment in these forms is the 

 tendency to collect in the epicone, especially near the apex, leaving the h^i^ocone 

 relatively free, though usually not entirely so, from the colored granules. In 

 Gyrodinium macuJatnm (pi. 6, fig. 62) the abundant, violet-colored pigment is 

 densely massed in the epicone, so that imder the low powers of the microscope 

 this part of the body appears almost black, while the smaller granules in the 

 h}"poeone are sufficient only to give it a violet tinge. 



A few exceptions to this general rule are to be met with. In Gyrodinium 

 postmaadatum (pi. 6, fig. 64) the color is massed at the antapical end, leaving 

 the anterior end of the body free from agglomerated masses of color. The 

 same condition is found in G. ruhricaudatum (pi. 10, fig. 116). In Erythropsis 

 scarlatina (pi. 12, fig. 128) still another modification is found. In the anterior 

 part of the organism the pigment is confined more or less closely to the periphery 

 of the body, while in the centroposterior part it occupies the interior of the 

 body with amoeboid ramifications extending through the c}i;oplasm. 



It is not uncommon to find, on the approach of cytolysis, that the color which 

 has before been completely diffused through the cj'toplasm becomes localized 

 or condensed into granules, the erythrosomes of Faure-Fremiet (1914). This 

 same condition may be produced by the addition of dilute acetic acid, as Faure- 

 Fremiet has showTi for the rose-colored specimen of Erythropsis pavillardi. 



