SPIROCHETA BALBIANIT AND SPIROCHETA ANODONTA. 15 
“chromosomes.” However, as was kindly pointed out to me 
by Professor Ray Lankester, the use of the term involves an 
assumption, for the nucleus in these Spirochetes is diffuse, 
rather like the conditions occurring in the Bacteria. It does 
not, then, necessarily follow that these rodlets of chromatin, 
which are numerous and not easily seen, are strictly homolo- 
gous with the chromosomes of the concentrated nuclei of the 
Metazoa.! Further, in carefully and successfully stained 
preparations, it is seen that these chromatin rodlets are 
disposed on a more faintly staining spiral or zig-zag structure, 
the so-called “‘karyosome” of Perrin, so that they may be 
only large chromidial granules. 
The cytoplasm of these Spirochetes is, as previously 
stated, apparently homogeneous and hyaline. It is not 
easily differentiated into ectoplasm and endoplasm, though 
in a few cases a slightly more granular endoplasm could, 
perhaps, be detected round the nucleus. ‘The outer or ecto- 
plasmic layer of the cytoplasm forms a definite cuticle or 
periplast, giving a distinct contour to the organism. The 
ends of the body in S. balbianii are rounded, as in the 
case of the type-species S. plicatilis. On the other hand, 
in 8S. anodonte they are pointed, a feature of the greatest 
interest, as I hope to show in the sequel. 
Perhaps the most interesting structural feature, or “ organ- 
ella,” possessed by the Spirochetes is a spirally wound 
_ membrane arising as a lateral outgrowth of the periplast, 
and extending nearly from end to end of the body. It has 
been called an “undulating” membrane. By means of 
special stains, such as gentian-violet and iron-hematoxylin, 
this membrane is seen to be approximately longitudinally 
striated, a feature not before recorded in these parasites. 
The question of the structure and significance of this 
“organella”’ is of the greatest importance, and will be con- 
sidered in detail in a later section. 
1 Sir Ray Lankester has since suggested to me that the term “nucleoid” 
would more correctly describe the condition of the chromatin in forms like 
Spirochetes than the term nucleus does. Owing to the numerous alterations 
