288 THE PROTOZOA 



in one of the three ways ; a certain number show the body extended nearly 

 in a straight line, with the free edge of the membrane much pleated, but as a 

 rule the body is curved, and then either with one principal bend, like a C, or 

 with several S-like serpentine bends. In either case the undulating membrane 

 is seen almost invariably to run on the convex side of each curve. In C-like 

 forms (Fig. 125, ^4) the membrane runs evenly along the outside of the principal 

 curve, and the myonemes parallel to it. In S-like forms (Fig. 125, B) the 

 membrane is often seen distinctly to be spirally twisted round the body, the 

 myonemes also exhibiting the same twist. In life the undulating membrane 

 performs, as its name implies, movements like those of a sail flapping in the 

 wind. Wave-like undulations run along it from one end to the other, but not 

 always in the same direction ; it has been observed that reversals of the move- 

 ments may take place, the waves first running in one direction for a time, 

 and then suddenly undergoing a change and running in the opposite direction 

 (Minchin and Woodcock, 42). 



Much confusion exists in the nomenclature of the parts of the trypanosome- 

 bodj% more especially with regard to the small body for which Woodcock's 

 term " kinetonucleus " (" Geisselkern ") is here used a confusion due to 

 differences of cytological interpretation. While it has never been doubted 

 that the larger body (N.) is a true nucleus, various views have been held 

 with regard to the smaller body (n.), which, summarized briefly, are as 

 follows : The older writers regarded it merely as an organ of the periplast 

 from which the flagellum arose. Stassano and Bradford and Plimmer re- 

 garded n. as a body of nuclear nature, and termed it the " micronucleus," 

 comparing it with the similarly-named body of Infusoria. Laveran and 

 Mesni! (464, 391), on the other hand, regarded n. as the " centrosome," the 

 name by which it is generally known in France. Schaudinn (132) emphasized 

 strongly its nuclear nature, and stated that n. was not a centrosome, but 

 nevertheless used for it the term " blepharoplast," by which it is still generally 

 known in Germany, although a true blepharoplast is a body of centrosomic 

 nature. Moore and Breinl (484) reverted to the centrosomic view, and termed 

 n. the " extranuclear centrosome," believing that it arose by division of the 

 intranuclear centrosome contained in the principal nucleus (N.). Hartmann 

 and Prowazek (63), on the basis of their nuclear theory of the centrosome (see 

 Chapter VI., p. 95), regarded n. as a body both of nuclear and centrosomic 

 nature, using for it the term " blepharoplast " ; so also Rosenbusch. Finally, 

 Doflein (7), who is not convinced of its truly nuclear nature, continues to 

 employ for n. the term " blepharoplast." With these many conflicting views 

 with regard to the nature of n., the basal granule has been either ignored or 

 overlooked, or considered as a mere " end-bead " of no particular importance, 

 or ranked as a centriole, as it doubtless is. The nomenclature used here is 

 based on the general theory that a centrosome, or its equivalent, a blepharo- 

 plast, is an achromatinic body of nuclear origin, but not equivalent to an entire 

 nucleus, and on the conviction that n. is a true nucleus, and therefore is not 

 to be regarded either as a centrosome or a blepharoplast. For a fuller dis- 

 cussion of these points, see Robertson and Minchin (80). 



The trophonucleus of a trypanosome is typically a vesicular nucleus con- 

 taining a karyosome in which is lodged a centriole. The karyosome varies 

 in size in different species, and is sometimes double or multiple ; in T. qranu- 

 losum the smallest forms have a single karyosome which buds off others as 

 the animal increases in size (Minchin, 478). By the method which is most in 

 vogue, however, for making permanent preparations of trypanosomes 

 namely, the various modifications of the Romanowsky-stain this structure 

 is seldom to be made out, and the trophonucleus appears generally as an 

 evenly-stained mass or as a dense clump of stained granules. It contains 

 a centriole, difficult to make out in the resting condition, owing to its being 

 embedded in the substance of the nucleus. The kinetonucleus consists 

 mainly of a mass of plastin impregnated with chromatin, staining very 

 deeply, rounded, oval, or even rod-like in shape. According to Rosenbusch, 

 the chromatinic mass of the kinetonucleus is to be regarded as representing 



