136 The Mieroscoj^ic Germ Theory of Disease. By H. C. Bastian. 
to occur in the fluids of the body is directly supported by some of 
the most interesting results of Dr. Sanderson's experiments con- 
cerning pyaemia. He tells us that in some of the lower animals 
artificial tuberculosis and pyaemia are often only different effects of 
the same cause. That is, that some of the same inoculating ma- 
terial may be introduced beneath the skin of two rabbits, and in 
the one a slow and more chronic set of morbid changes is induced 
(tuberculosis), whilst in the other more acute and rapidly fatal pro- 
cesses are estabhshed (pyaemia) . In the former animal no organisms 
are to be found in the blood, whilst the blood of the latter, according 
to Dr. Sanderson, is swarming with them. Changes in the character 
of the morbid process therefore may occasionally favour the presence 
of organisms. Nay, further, we see the same kind of difference in 
another way. Pyaemia and septicaemia as they occur in some of 
the lower animals differ in one very notable respect from the 
same diseases as they occur in man. Whilst in the lower animals 
bacteria are to be found in the blood of the living animal, in man 
they are always absent during life. With such facts as these before 
us, and others previously referred to concerning the absence and 
presence of organisms in blister-fluid from different individuals, it 
need not excite much surprise if we flnd that organisms are to be 
found in the blood of persons suffering from one or more of these 
specific contagious fevers. 
There are, however, three other diseases of this class in which 
organisms, though absent from the blood, are to be met with in 
those parts of the body which are severally the special seats of 
morbid change. The three diseases are— vaccinia, ovine small-pox 
(which seems to be altogether similar to the disease occurring in 
man), and typhoid fever. 
That the organisms of the vaccine vesicle have any significance 
other than from being possible instances of heterogenesis or arche- 
biosis, I find it difficult to believe. Even if the contagious property 
of the fluid be resident in some of its particles, as the observations 
of M. Chauveau and Dr. Sanderson seem to prove, still such 
particles may exist and yet not be the independent organisms 
existing in the same fluid. The fact that as the organisms increase 
in the fluid with age the virus loses its intensity, and the fact that 
it may remain potent even after prolonged periods of desiccation, 
are both of them strikingly opposed to the notion that the living 
organisms of the fluid are its active elements in a specific sense. 
On the other hand, it does appear, from the experiments of the 
late Dr. Henry, of Manchester, that vaccine virus loses its intensity 
when subjected to a temperature of 140° F. 
In ovine small-pox we have, as Dr. Klein's very interesting 
researches have shown,* a local appearance and active growth of 
* ' Proceedings of the Royal Society,' No. 153, 1874. 
