186 H. II. WOODCOCK. 



(g), the whole lying iu the ectoplasm, Avhich becomes greatly 

 developed to form the undulating membrane. 



In T. noctuEe the undulating membrane arises by the 

 anterior part of the body becoming much flattened laterally, 

 and, to a certain extent, drawn out dorsally by the spiudle, 

 the two ectoplasmic surfaces thus coming close together. 

 The well-developed, sinuous, axial spindle has now become 

 excentric in position, and strengthens, or rather itself con- 

 stitutes the free (dorsal) edge of the membrane, forming a 

 flagellar border to the same (h, f.h.) A supporting frame- 

 work is formed by eight myonemes, representing the eight 

 elongated chromosomes, four of them being arranged on 

 each lateral surface. The flagellar spindle does not stop on 

 reaching the anterior limit of the body, but continues to 

 elongate, drawing out with it the undulating membrane, 

 which narrows and finally thins out. The myonemes then 

 unite with the spindle to form the free flagellum, which 

 gradually tapers aAvay at its distal extremity. The centro- 

 some at this end disappears, as such, but that at the basal 

 or posterior end of the spindle persists (c"). The other 

 daughter-kinetonucleus has now become rounded off as the 

 functional kinetonucleus (h) ; it remains connected with the 

 complicated locomotor apparatus by means of the delicate 

 thread which represents the second axial spindle. In older 

 stages the kinetonucleus may pass backwards behind the 

 trophonucleus {t), pulling with it the associated structures, 

 which thus become even more extended (cf. fig. 13 g). 



The characteristic Trypanosome-form is now attained, and 

 the " indifferent " parasite next enters upon a period of mul- 

 tiplication by binary fission. The details of the process are, 

 Schaudinn says, too complicated for explanation without the 

 aid of numerous figures, so that only the main features can 

 be outlined here. The division of the nuclear apparatus is 

 the first to occur; either the tropho- or the kineto-nucleus 

 may lead the way. This is followed by the duplication of 

 the locomotor apparatus, which begins at its basal end, 

 starting either from the still undivided kinetonucleus or 



