272 
Spirochaetosis 
within 25 days. The eggs hatched after eight days under favourable 
conditions, such as those under which the female was kept; they did 
not hatch in the cold. Eggs kept near the person during the day and 
hung in clothing by the bedside during the winter in a cold room, did 
not hatch until the 35th day. When the larvae emerge from the egg 
they feed at once if given a chance to do so. They are prone to scatter 
upon the person and abandon the fragment of cloth to which the adult 
clings. The adult stage is reached on the 11th day after three moults 
occurring about every fourth day. Adults enter into copulation five 
days after the last ecdysis. The adults reared by Warburton lived about 
three weeks after the final moult, and the “ egg to egg ” period is reckoned 
at about 24 days. Unfed P. vestimenti adults died quickly at any 
temperature ; only one specimen survived in a feeble condition until the 
fifth day. Unfed larvae died in 36 hours. 
To this we may add that Nicolle and his colleagues find that both 
P. vestivienti and P. capitis survive longest when maintained at 28° C., 
in a damp atmosphere, being fed twice a day. 
I have allowed myself this digression, dealing with Pediculi, because 
Warburton’s results are doubtless unknown to many, and these parasites 
have only lately crept into prominence especially with regard to the 
etiology of typhus fever and relapsing fever. It is of importance to 
note how long the eggs may survive in view of the hereditary trans¬ 
mission of the spirochaetes in lice. It is obvious that the disinfection of 
verminous clothing is indicated as a preventive measure, and that those 
coming in contact with patients suffering from these diseases should 
promptly change their clothing and inspect their persons carefully after- 
exposure with a view to avoiding the bites of infected lice. 
Spirochaetosis in Cattle. 
The discovery of spirochaetosis in cattle is due to Theiler after whom 
the causative agent, S. theileri, has been named. The parasite is trans¬ 
mitted by the tick Boophilus decoloratus in Africa. Laveran and Vallee, 
to whom Theiler sent the infective ticks, reproduced the disease 
experimentally in France. That the ticks in this case become infected 
hereditarily goes without saying, for the infective ticks used by the 
French authors were larvae hatched from eggs laid by females which 
had fed on cattle harbouring the spirochaetes in South Africa. We lack 
observations to show if the ticks may remain continuously infective 
through several generations, as seen in S. duttoni-infected 0. mouhata. 
