EMBRYONIC DEVELOPMENT OF THE TELEOSTEANS. 43 



his, that they are embedded in a gelatinous substance. It is 

 not possible to isolate fragments of the cementing substance 

 — scarcely possible to see it between the eggs. 



My eggs have a diameter of 0*80 to 0*85 millimetres. They 

 are colourless, and present the transparency of crystal. The 

 membrane, which is very thin, shows neither canalicular pores 

 nor punctation of any kind ; it is homogeneous, of considerable 

 resistency, and very elastic. It is very difficult to tear it 

 ■without injuring the contained egg. 



The youngest eggs which 1 had under observation showed the 

 disc segmented into two spheres. They were brought to me 

 one morning about seven o'clock. I received two other masses, 

 the eggs of which were at the end of their segmentation ; they 

 had also been collected very early in the morning. It is probable 

 that the deposition of the eggs takes place during the night or 

 in the morning about sunrise. In all these eggs the form 

 was that of an ellipsoid, nearly a sphere, the major axis being 

 scarcely a sixth longer than the minor. At one of the extremi- 

 ties of the major axis (animal pole) is situated the germinal 

 disc or germ. This rests on the vitelline globe, which has the 

 same form as the egg itself, only the ellipsoid is truncated at 

 one of the extremities of its major axis along a surface, concave 

 at its centre, convex at its margin. From this results the for- 

 mation of a polar chamber, limited externally by the membrane 

 of the egg, internally by the vitelline globe. It is in this space 

 that the segmented germ is lodged. 



Tiie vitelline globe is formed by a hyaline substance, which is 

 perfectly homogeneous, colourless, little refringent, and devoid 

 of all structure. It holds in suspension a single solitary structural 

 element. This is a brilliant spherical mass, with very dark con- 

 tour, and occupies constantly the same position in the globe. 

 Excepting for this, the deutoplasm is absolutely devoid of any 

 granulation, of any vesicle or element which could be mistaken 

 for cell or nucleus. The substance which composes it is an 

 albuminoid matter ; it is coagulated by alcohol or osmic acid, 

 and is rendered turbid by acetic acid. The refringent sphere held 

 in suspension in the deutoplasmic globe is a drop of oil or of 

 fat. It is coloured black by osmic acid, and dissolves in ether. 

 Haeckel observed this same " Oelkiigel " in the eggs which he 

 studied, but the drop instead of being suspended in the vitelline 

 globe occupied the vegetative pole of the egg, and was simply 

 embedded in a spheroidal depression of the surface of the vitelline 

 globe. This is a characteristic which separates the eggs studied 

 by Haeckel from those observed by me. Owing to the circum- 

 stance that the specific gravity of the oily drop is less than that 

 of the substances which compose the other parts of the egg, the 



