24 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



in their movements, thougli data on this point are entirely lacking. In some 

 eases they are bilobed (pi. 10, fig. 108; pi. 12, fig. 132) and in others the two 

 pores are connected by slender canals. The latter condition may possilily be a 

 remnant of the ingestion area, by means of which a large food mass has been 

 taken into the body. This condition is more frequently f onnd in the more highly 

 specialized forms, to wit, in Coclilodiniu)ii, Poiicliefia. and Eri/tliropsis. 



The pnsule apparatus of the dinoflagellates usually reaches its greatest de- 

 velopment in the thecate forms, where daughter and accessory pusules are 

 formed (Schiitt, 1892; Kofoid, 1909), often of considerable complexity, and of 

 relatively huge size. They occur in species possessing chromatophores, though 

 their greatest development is reached where these organelles are entirely lacking. 

 No solid contents have been observed in the pusxdes or in the A-acuoles formed 

 from tliem. The connection of these cell organs with the kind of nutrition 

 existing in the absence of chromatophores and the fact that their greatest de- 

 velopment exists in the forms whose theea of discrete plates would materially 

 interfere with the ingestion of solid food strongly point to a sapro])hytic mode 

 of nutrition in zones of decaying plankton. These facts also lead to the con- 

 clusion that the pusules, at least the anterior one, function as a c}i:opharynx 

 for the intake of fluids and probably also of food particles into the body. The 

 possibility of food vacuoles and food balls being formed in connection with the, 

 pusules is not excluded. The canal frequently found connecting the anterior 

 and i:)Osterior pusules (pi. 7, fig. 76) suggests this possibility, since it probably 

 represents the remnant of an ingestion area which has included the entire inter- 

 cingular area of the sulcus. As has been pointed out in a previous paragraph, 

 it is evident from the size of the ingested organisms sometimes found in the 

 c^-foplasm that the entire area of the intercingular sulci;s must take part in the 

 process of ingestion. The channel connecting the two pores, lying at the prox- 

 imal and distal ends of this area respectively, would then probably persist as 

 the internal remnant of its jjrevious expansion, during which it functioned as 

 the mouth of the organism. 



Ocelli. — In the ocellus of the Pouchetiidae we find one of the most highly 

 specialized organelles among the Protozoa. Among the dinoflagellates it is 

 confined exclusively to this family, a shnilar structure not being present in 

 any other group. The more primitive red eyespot, or stigma, of fresh-water 

 Gyhinodininm is hardly the equivalent of tlie ocellus. 



The ocellate members of the Dinoflagellata were first observed by Pouchet, 

 who figured several species as members of the genus Gynmodinmm in a series 

 of papers from 1883 to 1887. The "organe oculaire," as he termed this peculiar 

 structure in the forms he observed, he described as a refractive, hyaline body 

 with one end Imried in a mass of dark pigment. He also advanced the suggestion 

 that it probal)ly functioned as a light-])erceiving organ. 



It was not, however, until the publication of Schiitt 's monograph (1895) 

 that any adequate description or figures of the ocellus were presented. He 



