THE MYXOMYCETES OR MYCETOZOA ; ANIMALS OR PLANTS ? 103 
Presidential address, chiefly relating to lower organisms, de- 
livered to the meeting of the British Association for the year 
1879. Others, taking an intermediate view of the question, 
have contented themselves with allotting this group a half-way 
position in the organic chain, Prof. Hackel, as previously 
notified, incorporating the Myxomycetes in his newly- established 
kingdom of the Protista, while Prof. Huxley* remarks of 
their flagelliferous monadiform germs that ‘ they are embryonic 
forms of organisms which appear to be as much animals as 
plants ; inasmuch as in one condition they take in solid nutri- 
ment, and in another have the special morphological, if not 
physiological, peculiarities of plants/ 
Being greatly impressed in favour of the evidence adduced 
in support of their animal affinities, the present writer has, in a 
general outline of the sub-kingdom Protozoa, included in Part I. 
of his Manual of the Infusoria , thought fit to accept the My- 
xomycetes, or Mycetozoa, as veritable Protozoa, indicating at 
the same time the very numerous points in which their structural 
and developmental phenomena tally with those of the more 
typical representatives of that zoological series. In this manner 
it was showm that the initial term or flagelliferous unit de- 
veloped from the spores of these so-called Fungi — possessing a 
nucleus, contractile vesicle and capacity to incept solid food 
particles — is in noways distinguishable from an ordinary 
representative of the genus Monas, as defined by the writer at 
p. 232 of the Manual quoted. The succeeding or ‘ plasmodium ’ 
phase of these organisms, likened by its describers to a colossal 
Amoeba, is similarly correlated by the writer (l.c. pp. 42 and 192) 
with Labyrintliula, and with the amoebiform masses produced 
through the coalescence of a greater or less number of primary 
flagellate zooids, out of which the reproductive gemmules of a 
sponge-body are built up.^f* The spore-receptacles, or sporangia, 
are finally interpreted as corresponding on an extended scale 
with the ordinary encapsuled or encysted conditions of the typical 
* Anatomy of Invert ebrated Animals, p. 44, ed. 1877. 
t An additional type, whose adult structure resembles in a remarkable 
manner the 1 plasmodium ’ condition of the Mycetozoa, is afforded by the 
Biomyxa vagans, as figured and described by Prof. Leidy in his recently pub- 
lished Fresli- water Rhizopods of North America, Washington, 1879. This 
organism, which inhabits the Sphagnum swamps of New Jersey and Penn- 
sylvania, and may be compared to a shell-less Gromia, protrudes lobate exten- 
sions, or anastomosing pseudopodia, in every direction, which exhibit a 
distinct granule circulation, while a greater or less number of contractile 
vesicles are developed, both upon the surface of the body and along the 
pseudopodial extensions. The likeness cited as subsisting between these 
correlated organisms is indeed so great, that Prof. Leidy has some doubts as 
to whether it represents an immature Mycetozoon or an independent 
Rliizopod. In one example figured, the central protoplasmic mass is filled 
with ingested Closteria. 
