G. H. F. Nuttall 
273 
About 14 days after such infective larvae are placed upon cattle, the 
latter develop spirochaetosis, but the infection appears to be mild. In 
Laveran and Valine’s experiments spirochaetes were only present in tbe 
blood for four days. Four days later, however, the animal developed 
piroplasmosis, proving that the ticks had transmitted a double infection. 
Koch, working in Africa in the same year (1905), likewise observed 
spirochaetosis in cattle and reported finding the spirochaetes in the eggs 
of a species of tick which he found upon the affected animals. 
This exhausts the list of spirochaetes concerning whose mode of 
conveyance we have definite knowledge. There are, however, a number 
of different animals infected by spirochaetes which are doubtless trans¬ 
mitted in a similar manner. Horses occasionally harbour spirochaetes, 
and so do sheep in Africa, and, judging from inoculation experiments, 
these spirochaetes are probably identical with S. theileri. Bats, as 
Nicolle and Comte found in Northern Africa, suffer from a typical 
relapsing fever due to 8 . vespertilionis which may be conveyed by 
several of the numerous ectoparasites infesting these animals: Argas 
vespertilionis and lice would naturally suggest themselves to me as being 
the probable vectors. 
Spirochaeta muris, occurring in rats and mice, and 8. gondi Nicolle, 
1907, occurring in a small African rodent (Ctenodactglus gundi) are both 
transmissible by blood inoculation and presumably in nature are trans¬ 
mitted by ectoparasitic arthropods. 
Cultivation of 8pirochaetes. 
Another important step in our knowledge concerning spirochaetes is 
that they can be cultivated in vitro. All efforts to cultivate them under 
ordinary conditions, suitable for the great majority of Bacteria, have 
given negative results in the hands of many bacteriologists all over the 
world. Levaditi (1900), it is true, succeeded in cultivating 8 . gallinarum 
and 8. diittoni in collodion sacks placed, according to the usual technique, 
in the peritoneal cavity of rabbits. Under these conditions the spiro¬ 
chaetes multiplied and lived for 73 days or more. Successful cultivation 
in vitro has, however, only been recently accomplished by Noguchi 
(August, 1912), by adding a few drops of citrated rat or mouse 
blood, contairring the spirochaetes, to sterile ascitic or hydrocele 
fluid (10 to 15 c.c.) in tubes containing pieces of freshly excised rabbit’s 
kidney. Precautions against bacterial contamination are imperative; 
