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Before proceeding to state the results of our experiments, 
a more complete account must be given of microzymes, and 
something must be said as to the views entertained by 
naturalists of their nature, origin, and relation to other 
organic forms. The methods of investigation which have 
been employed must also be explained. 
Bacteria or microzymes are placed by most naturalists in 
the animal kingdom, and have a position assigned to them 
next to the monads. MHallier, on the other hand, believing 
that they originate by the cleavage and multiplication of 
nuclei in the cells of fungi, and that they develop to the same 
forms from which they spring, regards them as plants. Their 
claim to be considered animals is founded partly on their 
motions, partly on the fact that their chemical reaction on 
air, when alive, resembles rather the respiration of animals 
than that which is associated with vegetation. The question 
is of importance only in so far as it involves that of origin 
and development. If it can be shown that they neither 
spring from higher forms nor grow to them, the discussion of 
their animal or plant nature may be left to those interested 
in verbal definitions. 
Microzymes grow either in liquids or moist air. In liquids 
they present different appearances, as they are observed in 
the depth or on the surface. In the former case they show 
no tendency to assume any special arrangement to each other 
if they are motionless ; nor if they are active are their motions 
governed by any mutual relation. At the surface of the 
liquid, on the other hand, although the individual bacteria 
show no definite arrangement when they first appear, they 
soon place themselves in such a manner as to form a mem- 
brane, the beginning of the bacterium scum, to which we 
shall have frequent occasion to refer. In this membrane, 
when it first appears, each rod stands vertically, one end 
forming part of the free surface, the other part of the deep 
surface of the membrane. The rods adhere together by their 
sides after the manner of the elements of columnar epithelium, 
but there is, I think, strong reason to believe that this adhe- 
sion is not direct, 2. e. that they are not in actual contact, but 
glued together by a viscous intermediary substance. Con- 
sequently on this arrangement the “‘ scum,” when first formed, 
presents under the microscope the aspect of an evenly dotted 
surface, the distance between each dot and its neighbour 
corresponding approximately to the diameter of a rod. This 
appearance, indeed, is so deceptive, that for a long time I 
supposed, as others have done, that the constituent particles 
were round; nor was it until it was discovered that the mem- 
