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PROGRESS OF MICROSCOPICAL SCIENCE. 
Bacteria in Organic Tissues protected from Air. — M. Servel re- 
cently read an interesting paper on this subject before the French 
Academy of Sciences. He said that bis experiments were suggested 
by some ineffectual attempts he made to harden large fragments of 
cerebral substance with chromic acid. If the tissue be not treated in 
thin slices, the central parts of the piece, not being reached by the 
acid, undergo putrefaction. In the five experiments now to be 
noticed be used a solution of chromic acid, containing one part in 100. 
The first two experiments were on guinea-pigs (in October, 1874). The 
live animals were decapitated so that the bead fell at once into the 
chromic acid bath. In both cases the results corresponded to those 
with the cerebral substance. Examined six days after immersion, the 
outer parts of the bead were bard and preserved ; but the central 
parts were in manifest corruption ; under the microscope, the cerebral 
pulp presented a large number of bacteria of all sizes. Feeling, 
however, that in these experiments the absence of air-germs was not 
sufficiently demonstrated, as the deep parts of the nasal fossae or the 
buccal cavity might possibly have retained them notwithstanding the 
immersion, M. Servel repeated the experiment with the liver or kidney 
of dogs, killed for this purpose by femoral bleeding. To eliminate 
sources of error, and especially entrance of air by the wound, be 
placed a ligature at the level of the bilum of the liver and the kidney 
to be experimented on ; then be completely removed these organs, 
preserving their envelope of connective tissue throughout its extent. 
The threads of the ligature were used to suspend the organs and keep 
them from contact with the sides of the vessel containing the solution. 
This experiment, repeated three times (in October and November) on 
two bunting dogs and a shepherd’s dog, gave the following results, 
after five days’ immersion (the average surrounding temperature being 
fifteen degrees [Centigrade] ). The liver and kidney were more volumi- 
nous than in the fresh state, elastic to pressure. The surface was 
hardened throughout, and gave the peculiar odour of organs immersed 
in chromic acid. On section, there was emanation of fetid odours. 
Under the microscope, the outer layer was found entire ; the central 
parts were full of bacteria, showing characteristic movements ; some, 
in the liver, were large, some enlarged at one end ( Bacterium capi- 
tatum ) ; in the kidney they were fewer, thinner, and more mixed with 
cells still intact. The solution of chromic acid at once arrested the 
movement of the bacteria. Hence M. Servel concludes : 1. That 
MM. Bechamp and Estor’s demonstration of the production and evo- 
lution of bacteria in organic tissues protected from air-germs is quite 
exact ; 2. That the effect produced by preservative agents is the death 
of microzymes or molecular elements surviving in the organs. 
Professor Williamson’s Deep-sea Besearclies. — Professor William- 
son, F.R.S., is known to have conducted some important inquiries 
into the marine Tertiary deposits, and therefore it is somewhat unfair 
