468 THE PROTOZOA 



apparatus with kinetonucleus and trophonucleus, and a locomotor apparatus 

 with flagellum and undulating membrane. Schaudinn further constructed 

 a hypothetical form of " Urhaemoflagellat " connecting the spirochaete and 

 trypanosome type of organization ; he put forward the suggestion (903) that 

 "as the general structural plan of a trypanosome (nuclear and locomotor 

 apparatus) may be found realized in various groups of Protozoa as a transitory 

 developmental condition (comparable somewhat to the gastrula- condition 

 in the Metazoa), so also the spirochaete may crop up occasionally as a morpho- 

 logical type in the development of Protozoa, and as a developmental stage 

 may indicate to us phylogenetic relations." 



Schaudinn lived long enough, fortunately, to retract many of his state 

 ments with regard to the structure of spirochaetes, and acknowledged that the 

 trypanosome-type of structure was not to be made out in the minute parasitic 

 spirochaetes. Nevertheless, since his time the investigators of these organisms 

 have been divided into two camps those who hold fast to Schaudinn's theory 

 of the spirochaetes as Protozoa, and those who class them with Bacteria, 

 respectively ; it being generally assumed, for some unknown reason, that it 

 they are not Protozoa they must be Bacteria, or vice versa. A third set of 

 authorities compromise by placing the spirochaetes in an intermediate position 

 between the two groups. 



In considering the question of the affinities of the spirochsetes, attention 

 has been directed not only to their structure, but also to their life-history ; 

 and a hot controversy has raged with regard to their mode of fission, whether 

 it takes place longitudinally, as in a trypanosome, or transversely, as in a 

 bacterium. Investigators contradict each other flatly with regard to this 

 point ; but from the most recent investigations it seems probable, at least, 

 that the division is always transverse, and that the appearance of longitudinal 

 division is due to the peculiar method of " incurvation : ' described by Gross 

 (Fig. 194). A spirochaete about to divide grows greatly in length, and one 

 end of the body doubles back on itself, continuing to do so until the recurved 

 limb of the body is of the same length as the remainder ; the two halves twist 

 round each other and produce an appearance which may be mistaken easily 

 for longitudinal fission ; but the actual division of the body takes place at the 

 point where it is bent over, and is transverse. 



With regard to the development, nothing has been found in the least con- 

 firmatory of Schaudinn's statements with regard to " Spirochceta ziemanni," 

 with the sole exception of the statements of Krzysztalowicz and Siedlecki (901), 

 who profess to have seen trypanosome-stages in the development of Treponema 

 pallidum ; but their statements are entirely unconfirmed by other investi- 

 gators. Of a very opposite type are the statements of Leishman (902) with 

 regard to the development of S. duttoni in the tick. The spirochaete appears 

 to break up into minute masses of chromatin, " coccoid granules," in the 

 ova and tissue-cells of the tick. The coccoid granules appear to develop into 

 spirochaetes again. 



The observations of Leishman have recently been fully confirmed by the in- 

 vestigations on the development of Spiroschaudinnia gallinarum published by 

 Hindle (900), who gives a useful diagram of the entire life-history. Bosanquet 

 (894) also observed the formation of coccoid bodies in Cristispira anodonice 

 by the segmentation of the elongated body into a number of coccoid bodies 

 like a string of beads. A development of this type suggests very strongly 

 affinities with bacteria, but none whatever with Protozoa of any class. The 

 coccoid grains may be compared with the spore -formation in bacteria, and 

 with that described by Gross (898) in Saprospira grandis. In all cases, through- 

 out the series of living beings, wherever an organism exhibits in its fully- 

 developed " adult " stage peculiarities of a special kind, it is above all to 

 the early developmental forms that the naturalist turns for indications of the 

 true affinities of the organism in question. 



Recently the structure of spirochaetes has been studied carefully by Gross 

 (897, 898), Zuelzer (904), and Dobell (895), by means of proper cytological 

 methods of technique. The results show a complete difference in every 



