1909.] 



On Trypanosoma eberthi [Kent], etc. 



389 



probably the kinetonucleus. The line along the base of the membrane stains 

 blue, while the blocks and edge of the membrane take up the eosin very 

 vividly. In hsemalaun preparations which have not been stained with eosin, 

 the blocks and the edge of the membrane may stain blue. 



B. The B Form (Trichomonas Condition). Figs. 2 and 3. — The B form 

 may be described as a typical Trichomonas of variable size, apparently 

 resembling the form described by Wenyon from the mouse. Usually the body 

 is more massive than in the A form, from which it is easily distinguished 

 by the presence of three long conspicuous flagella arising from the anterior 

 end. 



In all other points, nucleus, axostyle-line, and blocks, B agrees with A. 

 In living forms, two types of movement have been observed : one closely 

 resembles that of A, the undulating membrane being in active motion, while 

 the anterior flagella trail passively. The second type of movement is 

 characterised by the activity of the anterior flagella, which strike out in front 

 of the animal. In the films stained with hsemalaun and eosin, the anterior 

 flagella, which are longer than the body, are very conspicuous. i 



C. C Form (Monocercomonas Condition). Figs. 4 and 5. — This form 

 roughly egg-shaped. On the blunt extremity there is a well marked 

 cytostome, in the neighbourhood of which four long flagella rise. The body 

 is usually filled with food vacuoles containing bacteria, and the animal is 

 quite active even on the cold stage. The nucleus in the unstained forms can 

 sometimes be seen as a rather highly refractile spherical mass near the 

 anterior end, and there is no trace of an undulating membrane. In stained 

 forms there is no trace of the blocks or line ; the nucleus is a spherical object 

 with the chromatin condensed in the membrane, though in some cases there 

 may be a large internal karyosome. 



Possible Transitional Stages. 



In addition to these forms, small, rounded, generally motionless forms were 

 met with in which the typical nucleus and blocks of the A form were seen: 

 Besides these rounded forms, far more elongated forms were found with a 

 similar nucleus and the blocks ; these showed an indication of an undulating 

 membrane in the active motion during life. In these elongate forms ;a well 

 marked axostyle was seen. If we now return to the forms A and ,B, the 

 similarity between them in all other points except the absence of the three 

 anterior flagella in A is so great that it almost amounts to identity. On one 

 occasion we saw a living B form with an undulating membrane and posteriorly 

 directed flagella at 12.45 p.m. ; at 1.25 p.m. a distinct* split was seen along th0 

 middle of one of the three flagella. It is tempting to suppose that the change 



2 f 2 



