14 ANNIE PORTER 



others, that the longitudinal division described above is not 

 truly division, but is the resuit of agglutination or entanglement 

 of two parasites for the time being, and the séparation of the 

 associated forms again. Against this idea, I would advance the 

 following statements : 



F Were agglutination or entanglement responsible for the 

 condition described as longitudinal division, two parallel bodies 

 would be discernible along the Avhole length of the organisms 

 at some periods. This condition I hâve never seen ; 



2^ Forms with obviously one body but with double mem- 

 branes hâve been commonly observed, and also a membrane 

 has been seen to divide into two. Thèse changes are the early 

 stages of longitudinal division (see Fantham, I, 1908, PI. 2, 

 Figs. 13-17), and could not be produced by agglutination or 

 entanglement ; 



3° Spirochaeta haJhianii and S. anodontae live Avithin the 

 crystalline style of their Lamellibranch hosts. While the style 

 is of a viscid nature, it is of a différent consistency and compo- 

 sition from the blood plasma, which is the habitat of 8. duttoni, 

 S. recurrentis, etc. This différence in médium may account for 

 the agglutination effects so well seen in blood Spirochaetes, and 

 for the lack of such agglutination effects in the parasites of 

 Lamellibranch styles. 



BoRREL (1908) has recently advanced a new hypothesis 

 regarding the membrane of S. halhianii. He states that the 

 présence of a double membrane in a Spirochaete is not to be 

 associated with longitudinal division, but that it is présent 

 in every Spirochaete, and that the organism uses one mem- 

 brane in moving forward, the other when moving backward. 

 No mention of this remarkable character of the membrane 

 is made in the earlier paper by Borrel and Cernovodeanu 

 (1907), and no figures hâve yet appeared in confirmation 

 of this statement. In support of his conclusions Borrel writes : 

 « Lors de la division tranversale, qui est de toute évidence et qui 

 est marquée par l'allongement du Spirochète avec quadruple 



