294 KOFOID AND SWEZY. 



abundant in fresh smears and culture slides. There is no evidence 

 that this process of dropping off cytoplasm or plasmecdysis is pathologi- 

 cal. It seems to bear no relation to mitosis and the detached portions 

 which may also be detected after detachment in stained preparations, 

 contain no nuclear structures and no peculiar chromidia or vacuoles. 

 It may be one method of ridding the body of accumulated waste 

 products but there is no structural evidence of this. The amount of 

 cytoplasm thus dropped off may be nearly one half of the total mass 

 (PI. 1, Figs. 2, 5). 



Rounded, even spheroidal forms also occur, but these are, as a rule, 

 antecedent to, or attendant upon mitosis. The dimensions (Fig. A) 

 vary greatly. The majority of individuals are 18-28 jx in length and 

 8-15 IX in width. The smallest measured was only 11 /x long, but in 

 cultures, giant individuals 50 /x in length have been seen. If the 

 flagella are included the length attains 70-150 ^x. 



Since there is a series of intergradations between the largest and the 

 smallest forms (Fig. A) it is evident that they all belong within the 

 range of variation, or of growth. There is not the least evidence that 

 the stout (Fig. A, 6) and slender individuals (Fig. A, 7) are male and 

 female respectively, an interpretation often given in the life history 

 of flagellates to such extremes in shape, or as yet in our hands conclu- 

 sive evidence that the rounded forms have any sexual significance. 

 A rounded phase, however, antedates mitosis, and the smallest forms 

 are the result of multiple fission and may also be produced by rapidly 

 repeated binary fissions. In some cases the effect of this diminution 

 of size by division or by plasmecdysis is seen (Fig. A, 7) in the retention 

 of relatively large organelles such as cytostome, membrane, and 

 axostyle with a relatively small mass of cytoplasm (PI. 1, Fig. 3). 



There is no evidence that either large or small forms are found 

 exclusively or even predominantly in particular host species. Almost 

 the whole range in form shown in Figure A could be selected from 

 the teeming myriads of individuals in a single heavily infected host. 

 The differences in size and proportions seem not to l)e of a specific 

 or subspecific nature. 



The organelles of Trichomonas augusta (Fig. B) are those of the 

 typical trichomonad, to wit, nucleus (n.), cytostome {cyt.), vacuoles 

 {vac), and extranuclear motor apparatus consisting of blepharoplast 

 {hi.), three anterior {atii. fl.) flagella and an attached posteriorly 

 directed one, the last forming a part of the undulating membrane 

 {und. VI.) and projecting as a free flagellum (post.fl.) beyond the mem- 

 brane, the chromatic basal rod {chr. has. r.) or parabasal body, and 



