332 M. A. Schneider's Contributions to the 



The Rhizopod just described is probably identical with Ehren- 

 berg's Difflugia Enchelys. This is characterized as follows : — 

 " D. minima, lorica ovata, dorso rotundato, glabra, pellucida, 

 hyalina, 46 tam linese partem longa, processibus hyalinis, tenui- 

 bus, parvis, apertm-a laterali." This description, as well as the 

 figure (tab. ix. fig. iv.), agrees very well with our animal, except 

 the " lateral opening." The form or position of the foot may, 

 however, cause the opening to appear as lying more towards one 

 side. 



True double animals of our D. Enchelys are frequently met 

 with, — two bodies with membranous cases and nuclei being 

 attached to a common foot (fig. 20). The foot very often con- 

 sists only of a thin thread, but in other cases it exhibits all the 

 forms which have been described as belonging to the foot of the 

 simple animal. Both bodies are well filled with food. Three, 

 four or five bodies are frequently seen hanging together in the 

 same manner ; these however are by no means in the same 

 plane, but stand out from the foot in various directions. If 

 these animals are obtained in considerable numbers, the forma- 

 tion of these colonies by gemmation may easily be observed. 

 The foot is seen gradually to increase in size and acquire an oval 

 form. A new investing membrane and nucleus are then formed. 

 The offset is always equal to the parent animal in size. Like the 

 foot of a single animal, the common foot of two or more is, as 

 might be supposed, still in a condition to form offsets. 



A similar adhesion of Rhizopoda has already been frequently 

 observed. Cohn, in his ' Beitrage zur Entwickelungsgeschichte 

 der Infusorien *,' has brought together the instances of this in 

 a note, and conjectures that this adhesion is preparatory to a 

 copulation ; but may we not rather suppose that a gemmation 

 like that of D. Enchelys also takes place in other Rhizopoda ? 

 With Perty and Cohn I have also seen a pair oi Arcella vulgaris 

 attached to one another by their openings, of which one, exactly 

 as was observed by those naturalists, was provided with a white, 

 the other with a yellow shell. The white shell is probably newly 

 formed, and therefore indicates the young specimen produced 

 by gemmation from its companion. 



I have observed another mode of propagation in our Difflugia, 

 and although my observations have certainly not been frequent, 

 they have been sufficiently satisfactory. After I had kept a 

 great number of these creatures for some weeks in a clayey 

 sediment, the substance of the body, in all the individuals, con- 

 tracted into a ball. All foreign substances had previously dis- 

 appeared. The ball, which had a fatty outline, then divided into 



* Siebold iind Kollikcr's Zeitschrift, iv. p. 261. 



