PROGRESS OF MICROSCOPICAL SCIENCE. 
153 
incubation, followed by a period of disturbance, succeeded by a period 
of subsidence, and finally restoration to the normal state. There was 
also great increase of the infective material, and immunity from 
further attack by the same contagion. Saprophytes, of which the 
yeast plant and the bacillus are types, are the essential agents in all 
fermentations, decompositions, and putrefactions, the vast importance 
of which in the economy of nature and the life of man we are only 
beginning to realize. All the organisms hitherto found associated 
with infective inflammations and contagious fevers are of the tribe of 
bacteria, and in order to a fuller understanding of this association a 
further knowledge of the origin and attributes of these organisms is 
necessary ; a circumstance to which we have referred elsewhere in the 
present number (p. 152). In connection with the origin of these or- 
ganisms the aphorism Omne vivum e vivo had been assailed. It had been 
alleged that their origin may be spontaneous by a process of abio- 
genesis, and that they are not the agents but the products or accom- 
paniments of decomposition. These allegations are, the lecturer 
said, unsustainable, and he proposed to prove that these bacteria, like 
other organisms, arise from pre-existing parent germs, and in no other 
way, and that they are the actual agents in all decomposition and 
putrefaction. After a minute account of certain other experiments 
the author claimed to have established : 1st. That organic matter has 
no inherent power of generating bacteria, and no inherent power of 
passing into decomposition. 2nd. That bacteria are the actual agents 
of decomposition. 3rd. That the organisms which appear as if spon- 
taneously in decomposing fluids owe their origin exclusively to parent 
germs derived from the surrounding media. Facts, apparently con- 
tradictory to these propositions, were due to its being not understood 
till lately that while living monads are killed by a temperature of 
140°, the spores of the same variety of monad may survive a tempe- 
rature of 300°, and that therefore the spores of bacteria may probably 
survive the feebler heat of boiling water. The practical point to be 
noted is that a contagium consists in the majority of cases of an 
independent organism or parasite, and that all infective diseases con- 
form in some fashion to one fundamental type. If septic bacteria are 
the cause of septictemia, if the spirilla are the cause of relapsing fever, 
if the Bacillus anthracis is the cause of splenic fever, the inference is 
almost irresistible that other analogous organisms are the cause of 
other infective inflammations and of other specific fevers. The occa- 
sional production of diphtheria by scarlet fever, the author explained 
by the capacity for variation or sporting of the contagium in question. 
And in the same way he suggested an explanation for the otherwise 
unaccountable occasional outbreak of cholera in India ; the cholera 
virus in this case being an occasional sport from some Indian sapro- 
phyte which, by variation, has acquired a parasitic habit, and having 
run through countless generations, either dies out or reverts to its 
original type. In concluding, the author said, “ I believe that the 
doctrine of a contagium vivum is established on a solid foundation, 
and that the principle it involves, if fairly grasped in capable hands, 
will prove a powerful instrument of future discoveries.” 
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