﻿TREPONEMA PERTENUIS CASTEELANI OF YAWS. 445 



without covering the latter, and the line of the instrument be moved £ 

 or ] fx toward the treponema, the side of the loop will be hidden in most 

 instances. Whether it will be completely covered, or more than covered 

 by the line, we can not say. We can not be more definite than to say 

 that in our opinion the width of the organism is not far from 0.25 /x, but 

 it may be either greater or less. The length of the spiral turns averages 

 very close to 1.5 n, measured from crest to crest. When we first began to 

 study the organism we thought that Treponema perienuis was probably a 

 trifle wider and a trifle more open in its curves than Treponema pallidum , 

 and we yet think that this may possibly be true for the average of large 

 numbers, but our average measurements are the same for both, and there 

 is no form that we have seen which we felt justified in designating as 

 either pallidum or pertenuis, one and not the other, unless we knew the 

 source from which it was derived. 



Tbe curves of both species of treponema vary somewhat in width and 

 regularity, but these variations are not peexdiar to or even much more 

 common for either species. In general, the curves are fine, about 1 to 

 1.2 jx in depth, regular and rather rigid. The last-named character is 

 especially noticeable in unstained, fluid preparations. Here the organisms 

 are seen as fine and fairly rigid spirals, usually straight or almost so. 

 The appearance is the miniature of that produced by a long spiral wire 

 spring. Such a spring may be bent by slight pressures, but it at once 

 resumes its straight form when the pressure is relieved, and in either the 

 straight or the bent form it retains its spiral turns. 



This description applies particularly to fluid preparations from a few 

 hours to a few days old. In quite fresh preparations the treponema can 

 not usually be seen, or if seen, recognized. Flashes of very motile 

 organisms may be observed, and it is a fair presumption that some or 

 all of them may be treponema, but the motion is so rapid and the glimpse 

 of the organism so fleeting that no deductions can be drawn as to mor- 

 phological characteristics. 



It is important to note that in fluid preparations the morphology of the 

 organisms is much more regular than in stained ones, and it is therefore 

 probable that many of the variations in the latter class may be due to 

 tbe drying and staining process. This statement applies to our ex- 

 perience with both pallidum and pertenuis and we think that it lessens 

 tbe value of the deductions based solely on the morphology of stained 

 specimens. 



However, since the described morphology of both Treponema pallidum 

 and Treponema pertenuis heretofore rested almost entirely on the descrip- 

 tions of stained specimens, it is well to consider such specimens here ; but 

 it should be borne in mind, that no matter how many shapes, sizes and 

 forms the stained organisms may show, there is not one of them which can 

 not be imitated by the use of the spiral wire spring to which we likened 



