304 Elliot R. Downing, 



'•The eg"g' has now. long before the entrance of the sperm, 

 broken with the physiological traditions of the tissue in 

 which it originates: genetically it belongs to the ectoderm, 

 physiologicallj^ to the endoderm. The next change in the ego; 

 concerns its form again; whereas the projections from the margins 

 have heretofore formed only a small part of the volume of the egg, 

 they now come to make up the bulk of it, pushing out into the 

 surrounding tissue so that the egg is amoebaform and attains a 

 diameter of one mm. Among the granules and chloroplasts which 

 the plasma contains there appear bodies with sharp contours having 

 a diameter of -01 to "02 mm. If one presses the egg so that these 

 bodies are squeezed out into the water thej" appear to possess a 

 thick, dark, outer layer enclosing a clear space that is partly filled 

 by a thick mass: a clear drop seems to ooze from the interior, a 

 result which is hastened by the addition of sodium or potassium 

 hydrate. The clear inner substance contains fat droplets occasionally, 

 more often proteid particles which i-esemble much those that are 

 free in the plasma: stains show the outer layer and the inwardly 

 projecting portion to be thick plasma while the central clear sub- 

 stance is water. These bodies have given rise to a misunderstanding; 

 EcKEE mistook them for the embryonic cells and thought they arose 

 by a division of the egg; I shall call them pseudozellen. That 

 they are not cells there can be no doubt: they take no active part 

 in the formation of the embryo but remain as intracellular objects, 

 apparently reserve stuff that is finally absorbed. One finds them, 

 at first appearance, distributed in groups about the nucleus; they 

 often appear very suddenly. In the beginning they appear as small 

 spherical thickenings of the plasma which are distinguished from 

 the as yet uncolored chloroplasts only by their greater refractive 

 power: the central cavity soon forms and the projection grows into 

 it. The pseudozellen of H. aurantica and H. cjrisea differ from those 

 of H. viridis as the projecting ingrowth is wanting and its place 

 is taken by a thickening of the walls. These pseudozellen continue 

 to increase for a long time until they fill the entire egg except a 

 peripheral layer of protoplasm." 



"The egg now measures 1"5 mm along its long diameter, the 

 pseudopodia attain their maximum development. This stage is of 

 short duration: the projections are withdrawn, the egg assumes an 

 ovoid shape whose point turns centrad. The nucleus grows to 

 06 mm diameter: its plasma is drawn to a heap on one side, the 



