Scientific Memoirs by
where the temperature of the latter had been somewhat higher than it ordinarily
was, than in corresponding cultivations conducted at the ordinary atmospheric
temperature.
A loss of power for anaerobic growth was in these cases a result of cultiva-
tion on particular media, but such a loss does not manifest itself solely in
relation to transplantation to a new medium of different constitution from that
in which growth originally occurred, for it sometimes occurs to a greater or less
degree independent of any transfer, in cultivations, originally of anaerobic pro-
perty, which have been kept for prolonged periods. This came out very clearly
in a series of experiments which were tried some years ago on the effects of pro-
longed preservation of Agar-agar cultivations of Commas. At that time two
tubes of Agar-agar medium were simultaneously inoculated on the 3rd of March,
one from a tube-cultivation of a few days' duration, and the other from one
belonging to the same series and derived from the same source as the former,
but which had been established on the loth of December. In both cases free
growth occurred on the surface of the medium within twenty-four hours, but, while
the first tube showed the presence of very free intersticial growth, forming a dense
cloud all along the course of the needle-track, the second one showed hardly
an appreciable trace of the occurrence of any at all. Here also, as in the case
of, the phenomena present in connection with potato-cultivations, there was
distinct evidence of hereditary transmission of the modification in properties,
for, although capacity for free anaerobic growth was ultimately regained, it was
not regained immediately, but only gradually and in the course of repeated.
successive cultures in fresh media. Just as in the case of the potato-cultiva-
tions, the change in functional properties is associated with more or less altera
- t i o n i n f o r m , t h e g r o w t h p e r s i s t i n g i n t u b e s w h i c h h a v e b e e n p r e s e r v e d d u r i n g
prolonged periods, and which has lost anaërobic property, consisting in most
cases almost entirely of short, straight, almost micrococcoid particles in place
of normal Comma-Bacilli.
In certain cases a directly opposite result follows from prolonged cultivation
on one and the same medium, an acquisition of capacity for anaerobic growth
in place of a loss of such capacity manifesting itself. Instances of such an
acquisition came under notice not unfrequently in connection with potato-culti-
vations of species ε, as has already been pointed out.
The degree to which such acquired peculiarities are capable of being here-
ditarily transmitted varies in different instances, in certain cases, as those of
speciesβ andζ c o m p l e t e t r a n s m i s s i o n m a y g o o n f o r v e r y p r o l o n g e d p e r i o d s
and through very many successive generations of elements, whilst in others,
such as frequently occurred in connection with cultivation of species e, transfer
to the original kind of medium may be followed almost at once by a tendency to.
modifications which, in the course of repeated cultivations, lead to a complete
recovery of original properties within a comparatively, limited period,
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