'*'* 1*1 ^'.-"^ V" 1 .,.* 



202 University of California Publications in Zoology [VOL. 19 



observations, especially upon its metabolic character and nuclear 

 changes. The form has been identified as Collodictyon triciliatum 

 Carter (=Tetramitus sulcatus Stein). 



This genus was first described by Carter (1865, p. 289) as follows: 



Collodictyon, nov. gen. C. triciliatum, nov. sp. 



Pyriform, straight, or slightly bent upon itself, bifid at the small extremity, 

 presenting at the larger one an indentation, from which spring three cilia. 

 Structure transparent, cancellated, composed of globular cells, with a strongly 

 marked, greenish granule here and there in the triangular spaces between them. 

 Locomotive, swimming by means of the cilia; subpolymorphic, flexible, yielding, 

 capable of assuming a globular form ... or one more or less modified by the 

 body it may incept . . . ; enclosing crude material for nourishment in stomachal 

 spaces, and ejecting the refuse, like Amoeba. Provided with a nucleus and 

 contracting vesicles. 



He gave its habitat (p. 289) as "fresh water, chiefly among Euglena 

 and Infusoria of that kind." Its length was 1/771 in. (30/i) and its 

 location the Island of Bombay. Among his observations he added 

 (p. 289) the following: "The plastic nature of this Infusorium, and 

 its mode of incepting food being like that of Amoeba (for it does not 

 appear to possess any oral aperture), induce me to think that it should 

 be placed among the Rhizopoda. Still it seems to have some analogies 

 to Bodo Ehr." "Its generic name has been derived from its plasticity 

 and delicate cellular structure, which gives it a reticular or cancellated 

 appearance; and its specific designation from the presence of three 

 cilia." 



The above description is satisfactory for identification, though not 

 detailed. My own observations coincide with it with these exceptions : 

 there are four instead of three flagella; it may or may not be bifid 

 at the posterior end ; there is at the anterior end of the body a 

 blepharoplast from which the flagella arise, these not springing from, 

 but near the indentation, which is a continuation of the median groove, 

 or sulcus, which functions in food ingestion; I have found no con- 

 tracting vacuole, though Carter stated that he had observed ' ' contract- 

 ing vesicles" having no fixed position, but he figures none. 



In 1878 Stein figured a similar form, showing, however, the four 

 flagella, a median sulcus and a contractile vacuole, naming it Tetra- 

 mitus sulcatus. Kent (1880-1882, p. 314) accepted these organisms 

 as described by Carter and Stein as belonging to separate genera of 

 the family Trimastigidae, but that there is little cause for such a 

 distinction can be seen from his characterization of Stein's genus as 

 follows : 



