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observed in other vegetable cells which have not a firm
membrane. The characteristic mark of separation lies in the
formation of plasmodia or aggregation of swarin-cells.” ’
We find in the above paragraph the reasons why the Myxogastres
are placed outside the vegetable kingdom; these reasons
we further find to be two in number—one general, the other
specific. Commencing with the general reason, “ The group of
the Mycetozoa differs distinctly from the Fungi . . . in all such
characteristics as do not belong to all organisms alike.” In
estimating the value of the above reason, it will be most
satisfactory to accept De Bary’s own idea as to what constitutes
a standpoint for comparison, which is as follows—“ We find it
impossible to establish any strict homologies, and we are limited
to the observation of resemblances in form, structure, and mode
of life.” 2 As stated above, the Myxogastres are so far differentiated
as to have the vegetative and reproductive phases
sharply defined, and it is customary, I believe, to take the sum
of characters presented by both phases, in determining affinities ;
hence while admitting that reproduction is common to all
organisms alike, I maintain that differences of degree in
connection with reproduction, are also of value in determining
affinities, and consequently cannot reconcile “ the resemblance
of the Mycetozoa to the Fungi is due partly to their mode of
life and nutrition, partly to the close agreement in structure
and biological characters hehoeen their organs of reproduction and
the spores of Fungi ”—(the italics are ours)—with “ the group
of the Mycetozoa differs distinctly from the Fungi . . . in all
such characteristics as do not belong to all organisms alike ”—■
(italics ours)—especially as De Bary admits that in such simple
groups, our proofs of affinity are “ limited to the observation
of resemblances in forms, structure, and mode of life.”
Second, or specific reason.—“ The characteristic mark of
separation lies in the formation of plasmodia or aggregation of
swarm-cells.”
To realize the true value of the two points, both presented by
the vegetative phase, and considered by De Bary as of sufficient
’ Tom. cit. p. 443. 2 Tom. cit. p. 443.
importance to place the Mycetozoa outside the vegetable
kingdom, the formation of a plasmodmm in the Myxomycètes, or
the aggregation of sioarm-cells in the Acrasieae, the two primary
divisions of the Mycetozoa, it is necessary to commence with
the germination of the spore. In the Myxomycètes, the spores
on germination give origin to one, two, or more naked cells,
which possess the power of movement due to the protrusion of
pseudopodia or the presence of a cilium; these cells are known
as swarm-cells. The swarm-cells possess a nucleus, multiply by
bipartition, and eventually coalesce to form a plasmodium in
the following manner. After the production of numerous
swarm-spores by repeated bipartition, little groups are formed
by the close approach of two or more of these bodies; these
groups often disperse again, but eventually the components of
a group coalesce, and lose their individuality ; this coalescence
and loss of individuality results in the formation of a small
plasmodmm, which, in some unknown way, possesses the power
of attracting surrounding free swarm-cells ; these at once coalesce
and add to the bulk of the plasmodium. The nuclei of the
component swarm-cells retain their individuality in the plasmodium,
the latter retaining the power of motion originally
possessed by its components, and represents the vegetative
phase of a Myxogaster. The above is De Bary’s conception of
the formation of a plasmodium, to which may be added, in his
own words—“ Nuclei were not at first observed in the plasmodia.
Cienkowski even stated expressly that the nuclei present in
the swarm-cells disappear when they coalesce. But Schmitz
and Strasburger have recently established the presence of
numerous nuclei in the plasmodium, and it may be presumed
that they are the persistent nuclei of the swarm-cells and
products of their division.” ’ The presence of a thick, colourless
membrane surrounding the plasmodia in Lycogala, Arcyria
punicea, and Stemonitis fusca has been noted by De Bary, who
also found that in the last-named species, the inner and thicker
portion of the envelope became blue with iodine. Under
certain conditions unfavourable for active vegetative work>
‘ Tom. cit. p. 425.