INTRODUCTION. 5 



opinion " that no division of the Bhizopod 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, iii-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 Butschlif 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 Amwlse, 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 life of 

 the animal." 



Gruber supports his view by a reference to Pelo'iit//.ni 



* ' Atti Soc. Ital. Sci. Nat./ xix, fasc. 4 (1876). 

 t 'Morphol. Jahrb./ xi (1886). 



