314 H. M. WOODCOCK. 



Quite recently, Scliaudinn (148) has published a brief note on certain 

 " Spiroclisetre," which is of great assistance in deciding between these two 

 views. Part of a long individual of S. plicatilis, showing its form and 

 structure, is reproduced in fig. 64 a; on comparing it with fig. 63 a and c, 

 the general agreement between the two forms appears undoubted. Scliaudinn 

 describes a well-developed periplastic [ectoplasmic] undulating membrane en- 

 closing the endoplasmic axis of the body; in the latter lies the nuclear appa- 

 ratus, which, here also, has the form of a (fairly thick) thread on which is 

 suspended a single row of large chromatic grains. The type of nuclear 

 structure is manifestly the same as in "T." balbianii, but the spiral is much 

 more condensed. When, in addition, the rounded termination of the body 

 and the absence of any flagellum are noted, it seems obvious that in wliatever 

 group of organisms we place Spirochseta plicatilis we must also include 

 "T." balbianii. 



(b) Are the SpirochtetEe Trypanosomes, i.e. Fla- 

 gellates, or Bacteria? 



This question has been much discussed during the last 

 year or two. In Scliaudinn's great memoir he regarded 

 Trypanosoma ziemanni as possessing, in certain phases, 

 the actual characteristics of a Spirochaeta as then known; 

 and, further, he was iuclined to cousider that other Spiro- 

 chaetas (e.g. S. obermeieri of relapsing fever) were also 

 really only phases in the life-cycle of a particular Haemo- 

 flagellate. As a result of his more recent investigations on 

 Spirochajta, however, he finds that this is not the case, 

 but that the latter type of organism is essentially differeut 

 in character from a Trypanosome ; T. ziemanni, at certain 

 periods of the life-history, merely simulates a Spirochaeta 

 to a remarkable degree (see above, p. 244). 



The chief reasons for considering SpirocliEeta as a 

 Bacterial form rather than a Flagellate may now be briefly 

 discussed, since they bear upon the contrary view taken 

 below Avith regard to Spironema pallidum. 



(a) The bluntly-rounded ends, and the absence of any 

 indication of a flagellum in Spiroclueta are characters 

 whose importance hardly needs further emphasis. 



(6) The "undulating-membrane" of a Spirocha3ta, 



