OF THE PROTOZOA. EHIZOPODA, 203 



tint, and, vice versa, that by feeding- tlicm abundantly vnth such food, even 

 the animal substance of the ultimate cell acquii'ed coloiu*. Irregular accu- 

 mulations of colouring particles in the ultimate chamber are of rare occur- 

 rence. Ehrenberg has iigiu^ed such in Nonionhia germanica. 



The colomiess, or almost colourless Ehizopods, principally Amcehce, are, 

 owing to their transparency, visible with difficulty, and require nice adjust- 

 ment of the microscope and of the light to demonstrate their vitality and 

 movements. 



Concerning the chemical relations of the organic substance, it is stained 

 yellow or yellowish-brown by solution of iodine, like other proteine matters, 

 and, according to Schultze, is unaltered by diluted acetic acid, is slightly 

 hardened by a dilute solution of the alkahes, and more so by one of the car- 

 bonates. Moreover, its resistance to chemical action would seem to differ 

 in different species ; for the Gromia Dujardinii was the least affected of se- 

 veral animals experimented on. 



''The colouring-material," to quote the same writer, *' assumes by the action 

 of sulphiuic and of hydrochloric acids an intense verdigris green, and by 

 that of nitric acid, first a green and then a yellow tint. Concentrated sul- 

 phuric acid destroys the colouied substance, but when combined -svith sugar, 

 renders it green. By concentrated solutions of potash and soda, the coloui'ed 

 granules are dissipated without change ; and in ether and alcohol they are 

 readily and completely dissolved. In these reactions the coloming-matter 

 agrees with Diatomece, from which, no doubt, it is derived in the form of food." 



jS'o definite figure can be said to belong to the animal portion of the Rhi- 

 zopoda, owing to its capability of thro'wdng out processes in every direction, 

 of various dimensions and in different numbers, changing them almost every 

 moment. Auerbach, however, asserts of the Amcehce that they have normally 

 a spherical figiu^e. Dr. Bailey has pointed out the influence of pressure from 

 within, due to the various articles swallowed, in modifying the figure. The 

 Amoebce, being untrammelled by a shell, exhibit the Protean changes of form 

 in the highest degree, whilst the completely enclosed Foraminifera present 

 them in the lowest. In the latter the organic mass must follow the windings 

 of the canity of the shell (XXI. 24), and can escape only from the foramina 

 (holes) as thread-hke filaments, in the form, extension, and subdivisions of 

 which great latitude prevails. We have said that the sarcode of FoJythala- 

 mia follows the windings or adapts itself to the figure of each segment of the 

 shell, and has actually no figure of its own. However, when separated from 

 its calcareous investment by means of an acid, it retains the outline originally 

 imposed on it. ThiLS (XXI. 24) Schultze exliibits the sarcode substance of a 

 Miliola so separated, which shows a constriction at each half turn of the spii^al 

 and the deheate membrane which invests it or lines the shell. So, again. Dr. 

 Carpenter, in his description of Orhitolites, states that the soft sarcode body is 

 made up of a number of segments equal and similar to each other, and arranged 

 in concentric zones around a central nucleus. Among the Amcehce the varia- 

 ble processes may either be protruded at one time from eveiy portion of the 

 little mucous mass, so that, as Ehrenberg remarks of the Amoeba rcaJiosa, it 

 may, when fully outspread, be likened to a miniatm-e porcupine ; or, othei-wise, 

 they may be produced chiefly or entirely from one side ; or, as when the ani- 

 mal is moving, they are thrown forward in the direction it is progressing, and 

 retracted on the opposite side. Among many Monothalamia the bulk of the 

 Hying mass issues through the one large orifice, and can spread out in a similar 

 manner to the free Amoehhia, — the shell, according to the direction of the 

 pseudopodes, resting in the centre of the mesh or on one side. The Forami- 

 nifera have a like capacity of extruding their processes in one direction rather 



