502 



Dr. H. B. Fantham and Miss Annie Porter. [July 26, 



the free portions gradually increases, they diverge from one another, and 

 their appearance resembles that of the arms of a Y. The divergence 

 continues until, at the actual moment of separation, the two daughter 

 organisms are practically in a straight line, that is, there is an angle 

 of 180° between them. When the two individuals are quite free of one 

 another, they usually remain quiescent for a few seconds, and then move off 

 in different directions. 



Both S. duttoni and S. recurrentis divide longitudinally after the manner 

 outlined above. We have repeatedly seen this occur in life in both these 

 Spirocheetes, and also in S. balbianii and S. anodontce. The time required for 

 complete division is variable. The complete longitudinal division of 

 S. recurrentis has taken ten minutes, that of S. duttoni thirteen minutes, but 

 much variation was shown by different specimens. 



Transverse Division. 



Transverse division of Spiroohaetes of the blood has been definitely stated 

 to occur by various workers, but few of them state precisely what use was 

 made of living and of stained material respectively. Naturally, therefore, 

 details of the exact processes of transverse division are wanting. We have 

 made a careful study of the behaviour of living S. duttoni, S. recurrentis, and 

 {S. anodontce during transverse division, and under conditions resembling, as 

 far as possible, those that obtain in the host. 



Transverse division occurs in very long, thin individuals, whose move- 

 ments are somewhat slower than those of other Spiroohaetes in their vicinity. 

 The division is initiated by the appearance of waves passing from each end 

 of the organism towards its centre. When the waves reach some particular 

 spot at or near the centre that serves as a node, they meet and die out, 

 return waves passing rapidly in the opposite directions towards either end. 

 A second set of waves then passes from the ends in the direction of the 

 centre ; these meet and die out, and return waves, travelling in opposite 

 directions proceed to each end of the organism. These processes are 

 repeated many times, the velocity of the waves increasing meanwhile. As 

 time goes on, the nodal region of the organism becomes thinner, and finally, 

 after several extremely rapid sets of waves in succession, the tenuous centre 

 parts, and two complete short organisms are produced. The parent organism 

 appears to increase slightly in length during transverse division. The 

 individuals resulting from the division usually swim away in the ordinary 

 manner. 



The time needed for complete transverse division varies with the 

 individual Spirochsete, but we have observed specimens of both S. duttoni 



