1921] NATURAL SCIENCES OF PHILADELPHIA. 159 



a little behind the opening; it looks as if held in place by a basal 

 granule, and at the same time appears to be lengthened posteriorly, 

 like a hardly visible tracing, until it reaches a very distinct swelling 

 about level with the middle of the reservoir. This swelling is caused 

 by the presence, just outside the wall of the reservoir, of a large and 

 very distinct globule, or kinetonucleus. Opposite the kinetonucleus, 

 and on the other side of the reservoir, is the stigma, of a dehcate 

 brick-red tint; its form is that of a saucer, and seen from the side 

 looks like a crescent whose convexity is turned towards the reser- 

 voir. Viewed from the dorsal side, it is seen to be a small roundish 

 spot. In the immediate vicinity are sometimes seen very small 

 red particles, which later on will join the principal mass. The in- 

 ternal protoplasm, very clear, and with myriads of extremely fine 

 granules, is in its major portion occupied by a more or less con- 

 siderable number of rod-like elements, which look like chromato- 

 phores, but without color. These are needle-shaped, of a very 

 pure opalescent hue, generally 25 to 30[jl in length for only 2 or 3;jl 

 in breadth, and often even much thinner, especially those which 

 fill the posterior end of the body. They are set longitudinally, 

 imbricating upon each other, and lie along the whole length of the 

 body. They seem, in fact, to take the place of absent chromato- 

 phores, and if we keep in mind the statements of several observers 

 that green chromatophores are susceptible, under certain influences,^^ 

 of being reduced to the state of leucoplasts, it seems that in our 

 Euglena pseudomermis also we are entitled to think of the struc- 

 tures as leucoplasts rather than as paramylum bodies or any other 

 sort of pyrenoid. We might then consider this species as one of 

 those very rare green Flagellates, which have lost their colored 

 constituents, but which still keep the stigma, but only as a vestige 

 of a preceding state. 



Is this species, although deprived of true chromatophores, still 

 absolutely holophytic, or would it to a certain extent take food 

 from the outside in the form of microbes or particles of some other 

 form? I have found in several instances small vegetal particles 

 in the reservoir, and also inside the body protoplasm some small 

 vacuoles have been met with, which contained little granules, hke 

 food-vacuoles in fact, but the explanation might be different, and 

 the subject remains still obscure. 



About in the middle of the body is seen the nucleus, whose appear- 

 ance is most pecuhar. It is generally found as a spherule, sur- 

 rounded by a clear halo of lighter material, but this nucleus proper 



21 Light would be the more important agent. According to Zumstein (1900) 

 the chromatophores disappear as such in the dark, but persist as leucoplasts, 

 and reform into chloroplasts again if brought back into the light. Euglena 

 'pseudomermis was always collected with a small net dipped into the black mud 

 of the bottom of the ditch; it is quite possible that it lives in semi-darkness 

 inside that "organic felt" which is found carpeting the ground. 



