OF OECAFTHUS AND TELEAS. 



235 



ble in ether, which surrounds a greenish-yellow fluid readily soluble in ether. The 

 albuminoid bodies vary much in size and in their chemical composition. The latter 

 is proved by the varying results obtained from the use of reagents. The superficial 

 layers of many of them differ but little in their chemical composition from living 

 protoplasm. But since they do not exhibit any of the physical properties of the latter, 

 their substance must be considered as something different from protoplasm. The change 

 of the fat into the albuminoid, and of the albuminoids into living protoplasm, is undoubt- 

 edly entirely effected by the chemical or assimilative action of the living protoplasm of 

 the egg. When treated with osmic, acetic or chromic acid, the albuminoids are rendered 

 vesicular. They stain deeply in picro-carmine and acetic-acid carmine, but not in safra- 

 nine or alum-cannine. 



In the ovarian egg after the disappearance of the germinative vesicle no traces of nuclei 

 are to be found ; but bordering certain of the yolk masses there are bands of stainable 

 substance entirely similar to that which results from the degeneration of the follicular 

 nuclei, except that it is confined to a definite and limited area encircling some of the yolk 

 globules. (PI. 21, figs. 23, 24.) After fecundation no trace of distinct cell elements was 

 found until about the time of the appearance of the blastoderm. At this time the yolk 

 masses lie in contact with the vitelline membrane and the blastoderm cells coming to the 

 surface finally form a thin cellular layer between the yolk and the protective coats of the 

 ovum. Eggs were taken from the last ovarian follicle, from the oviduct, and from elder 

 stems where they had been deposited but a few (one to twenty-five) minutes ; they were 

 hardened in a HCl-alcohol preparation, removed from their protective membranes, stained 

 in picro-carmine, sectioned, and mounted in balsam. In none of them were there found 

 more traces of distinct nuclear elements than have been indicated above (pi. 21, fig. 23). 

 The earliest stage in which such elements were to be distinguished showed a partially 

 formed blastoderm, but from this time onward during the entire development of the 

 embryo there are always numerous amoeboid cells to be found throughout the yolk. In pi. 

 21, fig. 31 is represented a section through an egg in this stage, treated in exactly the 

 same manner as the earlier stages in which neither cells nor nuclei could be found. In pi. 



21. fig. 47, and pi. 23, fig. 7, are seen five of these cells 

 magnified 800 diameters, showing them to be both 

 naked amoeboid nuclei and amoeboid cells. PI. 21, 

 fig. 31, shows the manner in which the cells help to 

 form a blastoderm. The cell protoplasm extending 

 out from one surface of the nucleus fuses with a simi- 

 lar plate from the neighboring cell. The nucleus ex- 

 tends into this projection and here its membrane is 

 seen to be very thin. After these cells reach the 

 surface of the yolk they furnish by rapid division a 

 sufficient number of cells to form a membrane. 

 (Fig. 17 and Fig. 12, p. 233, show the completely formed 

 blastoderm.) The cells first arrive at the surface 

 in the lower part of the egg in the region in which the embryo is to be found at a later 

 period. 1 Only part of the amoeboid cells migrate to the surface. The others remain in 



1 Compare Brandt (10), Bobretzky (7), Weismann (41). 



Fig. 17. 

 Surface view of fresh serosa from an Oecanthus treated 

 with acetic carmine. X 500. 



