INTRODUCTION. 5 
opinion “that no division of the Rhizopod body into 
zones, sharply differentiated morphologically and 
physiologically, occurs, and that the interpretations 
which have been made in this sense are decidedly 
founded upon illusions.” His remarks had reference 
more especially to the publications of two authors, one 
of whom, Maggi,* had asserted the existence, not only 
of an endoplasm and an ectoplasm, but also of a ‘“ meto- 
plasm,” in which he supposed were seated the secretory 
organs of the Rhizopod, namely, the contractile 
vacuoles, whilst the ectoplasm served for locomotion 
and the endoplasm for digestion. The other, Brass, 
went somewhat further. He professed to distinguish 
within the Rhizopod body, and, indeed, in the Infusoria 
generally, as well as in the animal cell, four kinds of 
plasma, namely (proceeding from within outwards) 
the nutritive plasma, the food-plasma, the respiratory 
plasma, and the motor-plasma. These views had already 
been refuted by Biitschlit so far as they related to the 
Infusoria, and Gruber considered that Biitschli’s 
objections applied equally to Brass’s work, so far as it 
bore on the Rhizopoda. ‘ Whoever,” he remarked, 
“has long busied himself with the study of the 
Rhizopoda, knows how many species there are, 
especially among the dinwbz, in which, during life, no 
division into separate zones occurs; in which the whole 
of the contents of the bodies; as well as the nucleus 
and vacuoles, are irregularly whirled about, so that, 
for example, the nucleus (or the nuclei) may be at one 
time pushed to the extreme periphery, and then again 
flow back into the centre of the body. If in such 
Rhizopoda, after the application of reagents, an ap- 
parent separation into different. plasma-layers occurs, 
these may be definitely regarded as artificially produced, 
in face of the conviction arrived at during the hfe of 
the animal.” 
Gruber supports his view by areference to Pelomyaa 
* «Atti Soc. Ital. Sci. Nat.,’ xix, fasc. 4 (1876). 
+ ‘Morphol. Jahrb.,’ xi (1886). 
