LIVING SPIROCHAETES 21 



ves (figs. 9-12) were common in Anodons andOysters onafew 

 occasions. In one préparation most of the organisms were so 

 coiled. Tins préparation was observed carefully, using the 

 brightest liglit obtainable. Gradually under its influence, the 

 Spirochaetes uncoiled and in a short time there was no coiled 

 form to be seen, everyone had straightened and was performing 

 ordinary movements of progression and régression. 



VIII. — General remarks. 



In conclusion I may say that there appears to me to be no 

 évidence for sexual differentiation in Spirochaetes. The so-call- 

 ed « maie » forms, characterised by thinness, are best explained, 

 in the présent state of our knowledge, as forms resulting from 

 rapid longitudinal division. Similarly, the so-called « female » 

 forms hâve their relative thickness explained as being probably 

 that of full grown and normal forms which hâve not yet divi- 

 ded. There is no good évidence of conjugation among Spiro- 

 chaetes. Pseudo-encystment forms hâve already been discus- 



sed. 



It must be granted that there is great variation among the 

 forms of any given- species of Spirochaete, but thèse variations 

 are exphcable from the points of view of growth and division. 

 There is no justification for the création of many new species of 

 Spirochaetes (as has recently been donc by Schellack) from 

 closely related hosts — at any rate, in the présent state of our 

 knowledge — until there hâve been careful experiments on 

 cross-infection of the différent hosts. 



It also seems to me to be futile to discuss further the ques- 

 tion as to whether the Spirochaetes are Protozoa or Bacteria. 

 Undoubtedly they possess characteristics of each of thèse 

 great groups. In my opinion, the protozoal characters outweigh 

 the bacterial. This matter has been fully discussed by Fantham 

 (1908), NuTTALL (1908) and others. Fantham suggested a 



