i 5 4 SCIENCE PROGRESS 



Probably the undulating movements are principally due to the 

 myonemes of the body surface, while ordinary progression is 

 dominated by those of the membrane. 



Internal to the cuticle or periplast is an almost homogeneous 

 protoplasm, in which an inner, slightly more granular endoplasm 

 sometimes can be distinguished from an outer ectoplasm. There 

 is not a condensed nucleus as occurs in most Protozoa and in 

 the Metazoan cell, but the chromatin is distributed — in other 

 words, the nucleus is diffuse, an important fact first pointed out 

 by Laveran and Mesnil in S. balbianii. In well-fixed and 

 stained preparations of S. balbianii, the chromatin is seen to be 

 arranged in transverse bars at more or less regular intervals 

 {fig. 2, a). In the most successful preparations, a connecting 







a 



TlG. 4. — Diagrams of the nuclear helix as seen in Spirochetes, a. Loose helix, with 

 chromatin masses at the turns, connected together chiefly by achromatic substance. 



b. Shows scalariform rodlets of chromatin with slight amount of achromatic substance. 



c. Shows rodlets of chromatin, some thicker than others, because they were originally 

 arranged on a helix, and so were at different depths of focus, d. Shows arrangement 

 of the rodlets into dumb-bell shaped chromatin masses, e. Shows the chromatin in 

 longitudinal division of an organism, where the dumb-bell shaped chromatin masses 

 break across, and the halves contract towards the periphery, while the remains of the 

 chromatin threads "loop up" to form the chromatin apparatus of the daughter 

 organisms. (After Fantham.) 



spiral or fine zigzag filament is seen between the bars (figs. 2, c, d ; 

 4, a, [b, c, d, e). The filament does not stain so deeply as the 

 bars, and contains much achromatic substance. 



During division the chromatic spiral divides longitudinally 

 in the manner indicated in fig. 4 (a, b, c, d, e), each transverse 

 bar becoming dumb-bell shaped, and breaking across in the 

 middle. 



