CHAPTER IX.—MODE OF LIFE OF THE MYCETOZOA. 451 
Further investigation is necessary to determine whether other causes also may 
not assist in certain cases to give rise to the latter phenomenon ; the question also, 
whether the peculiar characters of plasmodia under discussion may not change at a 
certain period of their development in relation to other things, as well as to 
hydrotropism, has still t0 be examined, especially with reference to a statement 
of Hofmeister‘ that certain plasmodia moved towards the side of strongest 
illumination. 
To the movements which have now been described must be added one more 
which requires a brief consideration. It was stated above on page 425 that small 
solid bodies are engulphed in the substance of the plasmodia, at least in the Cal- 
careae or Physareae. This is effected by definite movements; the surface of 
the plasmodium rises cushion-like round the bodies which are in contact with it, 
and the margins of the raised part gradually run together over them and cover 
them. j 
This phenomenon occurs in the plasmodia, as soon as they have been formed by 
coalescence of swarm-cells, but not in the swarm-cells themselves, if we put aside 
certain isolated observations on Dictyostelium which have yet to be confirmed, It is 
not confined to any particular spot of the plasmodium, and may continue till 
sporangia begin to be formed; then the foreign bodies which have been absorbed 
and are still present are all ejected, some of them even at an earlier period. ‘All this 
shows, that the solid bodies are not simply squeezed into the soft and passive 
substance of the plasmodium; but that there is a reaction of the plasmodium 
in response to the stimulus which it experiences from contact with them. 
Substances of various kinds are taken in this way into the substance of the 
plasmodium: fragments of dead vegetable cells, spores of Fungi and of the 
Myxomycetes themselves, sclerotium-cells of Myxomycetes, grains of starch, small 
portions of colouring matters if brought near the plasmodium. 
All these substances it should be observed consist of organic compounds, and it 
is highly probable that some of them at least supply food to the plasmodium which 
has engulphed them. It is not certainly ascertained whether entirely indifferent 
inorganic substances are absorbed by it. The question therefore remains 
unanswered, whether the movements of engulphing are caused by the purely 
mechanical stimulus of contact, or by certain chemical qualities of the substance to be 
engulphed. In the latter case the phenomenon would rank immediately with the 
movement in the direction of nutrient bodies described above, and both would be 
special cases of a more general law of reaction in response to chemical irritants, An 
old observation of my own supports the view that the reaction not only is or may be 
dependent on a definite chemical quality in the body which causes the stimulus, but 
that plasmodia of different kinds react unequally on the same stimulation. A number 
of pieces of carmine were absorbed by Didymium Serpula, scarcely any by Chondrio- 
derma difforme. 
Section CXXVIII The process of nutrition takes place only in the 
amoeboid states of the Mycetozoa, in the swarm-cells therefore and the plasmodia. 
All the better known Myxomycetes in their actual primary adaptation are saprophytes ; 

1 Pflanzenzelle, p. 20. - 
Gg2 
