52
Infusoria: What are they ?
Artificial animal and vegetable macerations yield very
numerous forms, and are especially rich in the flagelliferous
Monads. Up to a comparatively recent date the derivation of
the Infusoria produced so abundantly in hay infusions has
been a marked subject of contention among physiologists,
some arguing that they were generated there spontaneously,
and others that they were developed from extraneously
derived pre-existing germs. By carefully conducted experi-
ments it has been my good fortune to successfully demonstrate
not only that the germs or spores of Infusoria abound in hay
previous to maceration, but also that the Infusoria which
produced these germs flourish in the living condition
in the grass previous to desiccation, remaining in a state of
temporary encystment during dry weather, and reawakening
to life with each shower of rain or fall of dew.3
A few concluding suggestions respecting the collection and
observation of Infusoria may not prove unacceptable. From
whatever sources samples of water containing specimens are
derived they should be kept separate, and have a label indi-
cating the place and date of collection affixed. Not only are
species mingled indiscriminately prone to prey upon each
other, but rare varieties may appear upon the scene whose
precise habitat cannot be successfully traced after such
admixture of the material collected. The student is advised
to habituate himself to make drawings, however rough, of
every species he encounters, placing by the side of each
sketch a registration of its precise dimensions, taken with
the aid of au eye-piece micrometer. The essential structural
points that he should further seek to verify are the position
and character of the oral and excretory apertures, and
similar data with reference to both the contractile vesicle
and the nucleus or endoplast if distinctly developed. The
nature and distribution of the cilia or other appendages will,
of course, receive primary attention; the precise number and
3 [The whole question of biogenesis versus abiogenesis is fully discussed
in chap. iv. of the 'Manual of the Infusoria'; and Mr. Kent's origins
and valuable observations, above alluded to, are detailed at length at
page 140, et seq., of the same work.—Ed.]