Miscellaneous. 161 
MISCELLANEOUS. 
Pelomyxa palustris, a freshwater Amoeboid Organism. 
By Dr. Richard Gkeef. 
The genus which forms the subject of this memoir was briefly de- 
scribed by the author in 1870, under the name of Pelobius ; but this 
denomination has been abandoned by him, on account of its being 
previously applied to a genus of Coleoptera. 
Pelomyxa palustris, the only known species, is found abundantly 
at all seasons at Bonn and Marburg ; but it is in spring and the 
beginning of summer that it seems especially to develop itself ; and 
it then covers the upper layers of the mud in great masses. It is 
observed in the form of little greyish bodies averaging 1 millim. in 
diameter, but sometimes attaining 2 millims., or even more. The 
smallest individuals are little points, scarcely visible with the simple 
lens. 
Under the microscope the contracted Pelomyxa usually appears 
spherical, ovoid, or lenticular. It is composed of protoplasm, in 
which two layers of different nature may be distinguished — a cortical 
layer, and a parenchyma. 
The outer layer, which appears to be pure protoplasm, is hyaline, 
homogeneous, and of a more viscid consistency than the parenchyma. 
It swells up into rounded vesicles projecting at the surface of the 
mass, and sometimes lobed or digitate, into which the inner surface 
penetrates as into a sac. These processes creep or flow by amoeboid 
movements, which cause the advance of the whole Pelomyxa. 
The inner parenchyma is of a more fluid consistency, and so closely 
filled with vacuoles that it appears quite reticulated. It seems only 
to take a passive part in the movements, and is merely carried in 
one direction or another as mobile contents under the action of the 
contractions of the outer layer. It is this inner substance that 
contains all the other parts, both those belonging to the organism 
itself and those which have penetrated from without. The very 
dark coloration which it often presents is due to the nature of the 
ingested food, which consists of animal and vegetable substances, to 
which a great quantity of grains of sand and fragments of mud is 
added. 
The vacuoles are of different sizes, and more or less closely 
packed ; and they constantly change their positions under the in- 
fluence of the amoeboid movements of the whole body. They are 
simple cavities, the perfectly clear contents of which rarely contains 
a few dark granules and is of a totally different nature from the 
enveloping substance. Dr. Greef believes that they contain nothing 
but water. 
Besides the vacuoles, there are in the inner parenchyma three 
sorts of distinct bodies — which Dr. Greef names nuclei ("Kerne"), 
shining bodies (" Glanzkorper "), and bacilli (" feine Stabchen "). 
The nuclei, which are always disseminated in great quantities 
Ann. & Mag. N. Hist, Ser. 4. Vol. xiv. 1 1 
162 Miscellan eo us. 
among the vacuoles, are thin-walled, usually spherical bodies, 
0-012 millim. in diameter, with hyaline contents, more or less 
furnished with dark granulations. By the examination of series of 
specimens, Dr. Greef convinced himself that these granulations 
become converted into larger rounded bodies, within which a puncti- 
form centre may be recognized. This centre enlarges simultaneously 
with the body which contains it, and soon leaves nothing more than 
a thin ring surrounding it. The envelope of the mother nucleus 
appears finally to burst under the constantly increasing influence of 
the nucleoles, which are found scattered in great numbers side by 
side with others still contained in their mother nuclei. The internal 
cavity of the nucleole constantly enlarges, so that the peripheral 
layer completely disappears, and there remains a simple, spherical, 
hyaline brilliant corpuscle with distinct contours. 
These bodies, when set free, continue to grow in the interior of the 
Pelomyxa ; and it is probably from them that the shining bodies, 
which must be regarded as the zoospores of Pelomyxa, originate. 
These shining bodies, which are easily recognizable by their aspect 
and size even under a low magnifying power, are disseminated 
through the inner parenchyma in still greater abundance than the 
nuclei. Most of them are spherical ; but some are oval or pyriform, 
or even irregular ; the smallest are not more than 0-006 millim. in 
diameter, and correspond to the corpuscles originating from the nuclei ; 
the largest are 0-06 millim. in diameter. They consist of a solid 
shining capsule, with perfectly hyaline and homogeneous contents. 
These shining bodies seem to be able to multiply in the interior of 
the Pelomyxa itself, by a constriction which separates them into two 
often very unequal parts. Otherwise no important change is to be 
observed in them so long as they are still enclosed in the inner 
parenchyma. It is outside this that they must continue their trans- 
formations. 
A Pelomyxa, which seemed to be dead and on the point of becoming 
decomposed, presented to Dr. Greef a totally unexpected spectacle. 
All round the animal there appeared a considerable number of little 
Arucebae, which soon surrounded the body of their parent in close- 
set bands. All these Amoebae had the same aspect and the same 
dimensions, and executed the same movements. "With a high power 
it was easy to detect in their interior a nucleus with its nucleoli, and 
a contractile vesicle. The constantly increasing circle of the Amoebae 
gradually dispersed ; and in about half an hour the movements 
became slower and feebler. Instead of amoeboid contractions of 
the whole body, nothing was to be seen but the extrusion of a few 
isolated, hyaline, lobed or digitate processes. The little Amoebae 
soon contracted, aud became spherical or pyriform. Then appeared 
a long undulating filament, which effected their transformation from 
the Amoeboid to the Flagellate form. Dr. Greef saw them move by 
means of this flagellum ; but he was unable to trace their ultimate 
destiny. It is consequently impossible to say whether the Flagellate 
form is developed directly into a Pelomyxa, or, as Dr. Greef thinks 
is more probable, only attains the latter phase after having passed 
Miscellaneous. 163 
again through the form of an Amoeba. The little Anicebse always 
issue perfectly formed from the body of the Pelomyxa, and they 
seem to originate from the shining bodies. The latter, therefore, must 
be regarded as germs or spores, originating in the nuclei. 
Besides the nuclei and the shining bodies, there are in the paren- 
clryma of the Pelomyxa innumerable fine hyaline bacilli, which are 
generally not more than from 0-006 to 0-008 milliin. in length. 
They are found free among the vacuoles, and often also adhere in 
great numbers to the whole surface of the shining bodies. Dr. Greef 
sometimes thought that he could perceive transverse strise at their 
surface and a longitudinal canal in their interior ; but he can assert 
nothing positive upon these points. Eeagents prove that they are 
composed of an organic substance. 
Dr. Greef concludes his memoir with some considerations on the 
affinities of Pelomyxa. He remarks that this creature resembles 
the plasmodium of the Myxomycetes, but that this plasmodium only 
represents a transitional state due to the coalescence of amoeboid 
spores, from which afterwards originates an organism of a much 
more complex structure, while the Pelomyxa represents the phase of 
of complete development, having numerous nuclei in its interior. 
Pelomyxa is consequently a multicellidar organism which represents 
a group of amoeboid creatures with multiple nuclei, belonging to 
the class Rhizopoda, and allied in many respects to the Myxo- 
mycetes. — Archiv fur mikrosh. Anat. vol. x. (1873), p. 51 ; Bibl. 
Univ. Dec. 15, 1873, Bull. Sci. p. 358. 
On Megapodius trinkutensis, Sharpe. 
By Arthur, Viscount Walden, P.Z.S. 
In the ' Annals ' of this year (xiii. p. 448), Mr. Sharpe described 
a Megapode from Trinkut island (Nicobars) as belonging to a species 
distinct from Megapodius nicobariensis, Blyth. 
At least four of the islands composing the Nicobar group are in- 
habited by a species of Megapode ; but as Mr. Blyth did not record 
the name of the island which furnished him with the type of his 
species, it is impossible to say which is the habitat of M. nicoba- 
riensis. A considerable series of individuals has recently reached 
me — consisting of six males, four females, and one unsexed from 
Camorta island, nine males, four females, and two unsexed from 
Nangcowry island, two males, three females, and one unsexed from 
Katschal island, and seven males, seven females, and one unsexed 
from Trinkut island ; and they all belong to one species. Every 
phase of plumage is represented ; and several of the Trinkut examples 
exhibit the French-grey tinge on the throat and sides of neck, as do 
some, but not all, from each of the other islands. Megapodius trin- 
kutensis must therefore be regarded as equal to M. nicobariensis. 
Three of the forty-seven individuals I have received present a 
feature not hitherto recorded, namely a tendency to assume a naked 
callosity on the crown, as is observable in Megacephalon maleo. One, 
a female from Katschal island, has the occiput and vertex naked of 
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