364 ALFRED GIBBS BOURNE. 



{" crystals " of Greef), to say nothing of its various other con- 

 tents. The vesicles contain a fluid substance impregnated 

 with chlorophyll. The vesicles and the bactei'ia are to be 

 regarded as bodies contained in the protoplasm, and the latter 

 may flow out leaving all its contents behind. When the proto- 

 plasm does flow out iu this way some of the bacteria soon follow, 

 and may then be seen to start an active movement; and if the out- 

 flow continues, the superficial vesicles leave the central mass 

 and may be seen isolated in the hyaline protoplasm (fig. 5). 



Protoplasmic Movements, Pseudopodia. 



Specimens of P. viridis will often remain for a long time 

 absolutely quiescent ; in such a condition the animal is, if not 

 flattened by a cover-glass, fairly spherical in shape, and the green 

 vesicles extend close up to the periphery. They always remain 

 embedded in the protoplasm, so that they do not actually come 

 to the surface ; and, indeed, there is at the surface something 

 more than the mere envelopes of the most superficially placed 

 vesiculae, or else the margin of an optical section would pre- 

 sent a sinuous curve, the sinuosities of which corresponded to 

 a row of vesicles, which is not the case. 



In specimens where movements are taking place these move- 

 ments are usually very active, and most so at the periphery, 

 although they are by no means confined to that region. 

 In this matter P. viridis agrees with other species of 

 Pelomyxa.^ 



Long-continued movements often take place without the 

 protrusion of any pseudopodia. Owing to its great size, P. 

 viridis, and, indeed, other species of Pelomyxa, move about 

 from place to place, at any rate while under observation, less 

 frequently than smaller amoeboid organisms. 



When the movements, which result neither in the protrusion 

 of a well-marked pseudopodium nor in a translation of the 

 organism, are taking place, the margin of an optical section 

 consists of a hyaline layer, the movements in which have a 

 wave-like, undulating appearance. It looks as though the 



' Bronn, 'Protozoa,' p. 97, foot-note. 



