90 Uviversity of California Publications in Zoology [Vol.16 



Lying against the anterior surface of the nuclear membrane is 

 the rather large blepharoplast from which the motor apparatus arises. 

 This consists of three equal anterior flagella. about 2.5 times the length 

 of the body (pi. 12, fig. 4) in length, together with an undulating 

 membrane which passes backwards on the surface to the posterior end 

 of the body and terminates in a trailing flagellum. The membrane 

 is well developed, often having a width of 2 or 3/x, and is bordered 

 along both edges by deeply staining lines, the outer or chromatic 

 margin is very slender, and the one at the line of attachment to the 

 body, the chromatic basal rod. or parabasal body, is slightly thicker 

 and more conspicuous by reason of its deeper stain. The membrane 

 is without granulations or apparent structure. The outer margin 

 greatly exceeds the inner one in length and is thrown into 5-10 ripples 

 or folds (pi. 12, fig. 2). 



The membrane is in eon.stant motion in the living animal, undu- 

 lations pa.ssing from the anterior end po.steriorly through the length 

 of the membrane. The whole structure closely resembles in its details 

 the same organelle in Trichomonas, and in the living condition the 

 animal is easily mistaken for a species in that genus. 



The protopla.sm is alveolar and shows no differentiation into ecto- 

 plasm and endopla.sm. neither is there any definite, structurally differ- 

 entiated pellicle present. The contour of the body is quite regular, 

 with few or no amoeboid tendencies which might be expected from 

 the lack of a definite pellicle. Such movements are very pronounced 

 in Tricliomonas (Kofoid and Swezy, 19156). No indications of food 

 particles have been observed in the protopla.sm. There are, however, 

 numerous fluid-filled vacuoles ranging in size from 0.2-2/x crowding 

 the protoplasm at all stages except in a narrow zone about the nucleus. 

 The.se are smaller and less di.stinct during multiple mitosis (pi. 12, 

 figs. 12-17). 



IMlTOSIS 



Owing to the extremely minute size of Triclwmitus parvus, the 

 process of binary fission is very difficult to follow in all its details. 

 A sufficient number of stages have been found, however, to indicate 

 that division is by a simple form of mitosis comparable with that 

 described for Trichomonas (Kofoid and Swezy, 1915a). 



The beginning of the process is the division of the blepharoplast 

 (pi. 12, fig. 4), and probably of the undulating membrane, though no 

 actual evidence on this latter point has been obtainable thus far. As 



