244 SECOND PART.—MPCETOZOA. 
highly differentiated Acrasieae, on the other into forms which produce plasmodia. 
Plasmodiophora, which will be further noticed below, is perhaps one of the simplest 
representatives of the latter kind, though this must remain uncertain for reasons 
which will be stated. In the group of the Myxomycetes the type becomes highly 
differentiated. - 
From these naked Amoebae with which the Mycetozoa are connected in the 
ascending line, the zoologists with reason derive the copiously and highly developed 
section of the shell-forming ‘Rhizopods,’ as they are understood by Fr. E. Schulze and 
Biitschli, though the course of their ontogenetic development is still imperfectly 
known. And since there are sufficient grounds for placing the Rhizopods outside the 
vegetable and in the animal kingdom, and this is undoubtedly the true position for the 
Amoebae which are their simpler and earlier forms, the Mycetozoa which may be 
directly derived from the same stem are at least brought very near to the domain of 
zoology. It has been already pointed out that the Mycetozoa show only a slight 
agreement, either in the general course of their development or in the characteristic 
features of its separate stages, with organisms which are of.undoubted vegetable origin, 
whether they be Fungi or plants other than Fungi; the agreement, with the exception 
of the few cases in which cellulose makes its appearance, is confined to phenomena 
which are common to all organised bodies. It is exactly in the species, which like 
Lycogala and Fuligo are most like the Fungi, that the agreement is of the smallest 
possible amount, being confined to purely external marks such as those between birds 
and winged insects. On these various grounds, which have been worked out at 
different times with greater or less clearness according to the state of our knowledge, 
I have since the year 1858 placed the Myxomycetes under the name of Mycetozoa 
outside the limits of the vegetable kingdom, and I still consider this to be their true 
position. 
We may further enquire whether closer ties of relationship do not appear at 
some point or other between the group of the Mycetozoa at their lower limits and 
members of the vegetable kingdom. In the search for these and judging by known 
facis, we find that the only forms which we can take into consideration are the 
Chytridieae which have no mycelium, as Synchitrium, Olpidiopsis, Rozella and Woronina 
(see sections L-LII). It has been already more or less distinctly stated that these forms 
are nearly related to the Mycetozoa. They agree with the Myxomycetes, first in the 
peculiar circumstance that the entire vegetative body is finally transformed into one 
many-spored sporangium, secondly in the fact that their spores and the vegetative 
body itself in the young state have the power of amoeboid movement for a longer or 
shorter time. But these are phenomena which are common to them and many other 
Thallophytes, with which no one ever has supposed or ever will suppose them to have 
any near affinity, Botrydium for example or Porphyra ; it is plain also that they have 
been appealed to from a wish to find some group of undoubtedly vegetable forms in 
which the Myxomycetes could be included. Of the characteristic phenomena of 
development in the Mycetozoa, the Chytridieae mentioned above show nether the 
aggregation of the Acrasieae, nor the formation of plasmodia by coalescence of swarm- 
cells. If the term plasmodium has in their case been used to describe bodies 
originating in the growth of a single spore, this arose either from an erroneous idea 
(Cornu), or it is a misuse of the word, for though Chytridium in its young state often 
