At a recent meeting in London, of the Royal Miscroscopical Society, Dr.
Dallinger gave his annual address to what was probably the largest
gathering of Fellows ever assembled on a similar occasion. After briefly
referring to the increased interest lately manifested in the study of
minute organisms, and recalling the characteristics of the doctrines of
abiogenesis and biogenesis, he passed rapidly in review the results of
the observations of Tyndall, Huxley, and Pasteur as bearing upon these
questions, and called attention to the observations of Buchner as to the
transformation of _Bacillus anthracis_ and _Bacillus subtilis_, and _vice
versa_, and referred with approval to Dr. Klein's criticisms thereon.
Having spoken of the desirability of careful and continuous study of this
class of organisms, and the importance of endeavoring to establish the
relation of the pathogenic form to the whole group, he said he should be
better able to deal with the subject by recording a few ascertained facts
rather than by making a more extended review, and he therefore devoted
the main part of his address to a description of "the life history of a
septic organism hitherto unknown to science." In his observations of this
form--extending over four years--he had the advantage of the highest
quality of homogeneous lenses obtainable, ranging from one-tenth to
one-fiftieth of an inch, his chief reliance being placed upon a very
perfect one thirty-fifth of an inch; and from the continuous nature of
the observations as well as the circumstances under which they were
carried on, dry lenses had for the most part to be employed. Having in
his possession a maceration of cod-fish in a fluid obtained from boiled
rabbits, he found at the bottom of it, when in an almost exhausted
condition, a precipitate forming a slightly viscid mass, to which his
attention was particularly directed. It was seen to contain a vast number
of _Bacterium termo_, but on examination with a one-tenth inch objective
showed that it also contained a comparatively small number of intensely
active organisms--one being discovered in about eight or ten drops of the
sediment. These measured 1-10,000 of an inch in length by 1-19,500 of an
inch in breadth. The fluid had originally been kept at a temperature of
90° to 95° F., and it was noticed that, when placed upon a cold stage
under the microscope, the movements of the organisms became, gradually
slower, until at last they entirely ceased; the necessity, therefore,
arose for the use of a warm stage, and the very ingenious contrivance by
which a continuous and even temperature was maintained within the
one-tenth of a degree was exhibited. The greatest difficulty in the
matter was, however, experienced in obtaining specimens for observation,
in order to be able to trace them from their earliest to their latest
stage. The President then explained, by means of an admirable series of
illustrations projected upon a screen by the oxyhydrogen lantern, the
life history of the organism to which he had referred, exhibiting it
first as a translucent, elliptic, spindle-shaped body, with six long and
delicate flagella, the various positions in which the five specimens were
drawn giving a very good idea of its peculiar porpoiselike movements.
The various positions which it assumed in making an attack upon a portion
of decomposed matter were also shown, the movements quite fascinating the
observer by their rhythmical character. The supposed action of the
flagella in the production of the movements observed was explained,
distinct evidence being afforded of a remarkable spiral motion, at least
of those behind. The process of fission was illustrated in all its
observed stages from the first appearance of a construction to that of
final and complete separation, the whole being performed within the space
of eight or nine minutes. A description of the process of fusion from the
simple contact of two organisms to their entire absorption into each
other followed, as well as their transformation into a granular mass,
which gradually decreased in size in consequence of the dropping of a
train of granules in it wake as it moved across the field. The
development of these granules was traced from their minute semi-opaque
and spherical form to that of the perfect flagellate organism first
shown, the entire process being completed in about an hour. Experiments
as to their thermal death-point showed that, while the adults could not
be killed by a temperature less than 146° F., the highest point endured
by the germs was 190° F. Illustrations of a variety of other modes of
fission discovered in previous researches on similar forms were given,
showing the mode of multiple division and a similar process in the case
of an organism contained in an investing envelope. The President
concluded his address, which was listened to throughout with the greatest
attention, by remarking that, though the processes could be seen and
their progress traced, the _modus operandi_ was not traceable. Yet the
observer could not fail to be impressed with the perfect concurrent
adaptation of these organisms to the circumstances of their being; they
were subject to no caprices, their life-cycles were as perfect as those
of a crustacean or a bird, and while the action of the various processes
was certain, their rapidity of increase and the shortness of their life
history were such that they afforded a splendid opportunity of testing
the correctness of the Darwinian law.
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