Attention is recalled to the existence in the blood of motile filamentous elements, highly suggestive of living organisms. They occur in normal blood as well as in various pathological conditions.
It is suggested that some at least of the forms described by Couvy and by Verwoort from Dengue and allied fevers may well be of this type. Incidentally the same may be said of the spirochetes described by Blanchard and Lefrou in the blood of Blackwater fever.
The use of the iron hematoxylin stain of Heidenhain after wet fixation in Bouin's fluid affords a means of distinguishing these spirals from true living organisms, although their differentiation from any forms known at present should not be difficult under the dark field once the existence of these forms is taken into consideration.
Some evidence has been adduced in support of the opinion that the platelets rather than the red cells are the main source of these filaments.