The resistance of the bacillius No. 4: to even pure glycerine is no doubt due to-
-the formation of spores by this organism and causes it to assume a relatively
greater abundance in glycerinated paste titan in the original vesicular matter.
The -use of lanoline as a preservative gives in practice very good results, and
whether affecting the organisms as glycerine does or not it certainly prevents the
putrefaction of the vesicular matter which would otherwise rake place. Some
experiments made by rubbing up pure cultures in lanoline afterwards kept in closed
tubes have however shown that after several weeks a distinct reduction in the
number of contained organisms may take place.
Organism.
.
Colonies in one 1oupful of mixture.
End of first
End of
End of third End of fourth
week.
second week.
week.
week.
Staphylococcus albus
...
...
...
...
1,424
437
27
22
staphylococcus aureus
...
...
...
..
6,782
1,632
642
603
86
staphylococcus citreus
...
...
...
...
1, 437.,
123
756
Bacillus No. 4
...
...
...
..
12,325
8,437
2,575
2 , 0 8 6
The experiments have from pressure of other work not been further pursued,
but they serve to indicate some important points in connection with the bacterio-
logy of vaccine. Collected under conditions of thorough cleanliness vesicular
matter does not as might be supposed swarm with organisms of all kinds. Very
often the only abundant organism is the Staphylococcus pyog enes albus. The
presence therefore of organisms other than those mentioned would at once
attract attention. Again in experiments with glycerine and other preservatives it
is almost useless to deal with the total number of colonies. Almost certainly the
great bulk will be the harmless saprophytic skin coccus, present also on every
human skin, and the information more to be desired is the action on individual
pathogenic organisms, some of which like the spores of trichophyton may be very
resistant. The distinction between the inhibitory and destructive action of pre-
servatives is also very clearly shown.
APPENDIX V.
THE DEVELOPMEMT OF PIROPLASMA CAN-IS IN THE TICK.
By the SUPERINTENDENT .
Even before Ross had demonstrated the part played by the mosquito in the
transmission of malaria two American observers Smith and Kilborne had shown
that Texas fever in cattle, a disease due to the presence of Piroplasma bigeminum,
a protozoon parasite of the blood corpuscles, was conveyed by the bite of ticks.
The extraordinary feature of this transmission was the fact that it took place
not by the bite of a tick which had fed on a sick animal, but by the progeny of
such a tick. Since this time no fact in the pathology of the infectious diseases has
been more firmly established than that ticks act as the carriers of the piroplasmata,
:as mosquitoes do. of filaria and malaria, and the tse-tse flies of trypanosomiasis.
Whether a developmental cycle occurred or not was less certain. That infection
passed through th.e egg and even in some cases through two changes of the skin of
t h e y o u n g t i c k m a d e i t v e r y p r o b a b l e ; b u t n o a c t u a l o b s e r v a t i o n o f s u c h a c y c l e
existed. Conjecture as to what this cycle might be was further added to by the
increased attention given to the piroplasmata as a result of Schaudinn's researches,
8