232 BUMPUS. [Vol. V. 



to right, the anterior border curving considerably less than the 

 posterior (PL XIV, H ; PL XV, 4). From the side it appears as 

 a considerable re-entrant of the even contour, giving a more 

 or less reniform outline. The coagulating effect of nitric acid 

 beautifully shows the disposition of the neighboring protoplasm. 

 It is, in the first place, as will be seen by reference to the figure 

 (PL XIV, H), abundant around the blastopore. It forms an 

 isosceles triangle, the acute angle of which extends posteriorly 

 from the inverted base, which is the straightened anterior bor- 

 der of the gastrula mouth. Extending laterally from this base 

 two lines of thickened protoplasm are seen to diverge, and, as it 

 bends anteriorly, each becomes wider until about one-third of 

 the circumference has been traversed (PL XIV, Fig. H Pel.). 

 Ultimately each enlarges until the clouds almost fuse in the 

 median line. A large U is thus formed, the enclosed portion 

 of which is relatively poor in protoplasm. Other portions of 

 the surface show no peculiar protoplasmic accumulations. 



If eggs at this stage, as well as those somewhat earlier or 

 later, are allowed to remain in alcohol for several days, espe- 

 cially if they have been previously hardened in hot picro- 

 sulphuric acid (Kleinenberg's), the capsule swells and the 

 enclosed egg contracts. The space thus formed is at first filled 

 with a cloudy fluid which finally clears in eggs of long standing. 

 When the capsule is ruptured, the enclosed egg rolls out. The 

 surface of the naked egg appears smooth and shining, and if 

 not punctured will remain in stains for hours without being 

 affected. The surface, in fact, appears to be cuticularized, a 

 point which bears on the formation of the blastodermhaut. 

 Extending posteriorly from the blastopore is a small whitish 

 cloud which appears to be beneath the surface. It will be 

 shown by sections to be the entoderm. 



PL XV, Figs. 3 and 4, represents an egg which has been 

 stained and rendered semi-transparent. The blastopore (Fig. 

 4 Gm) is by all odds the most prominent feature. Crowding 

 about it are innumerable cells, the lips of the blastopore and its 

 cavity actually swarming with nuclei, many of which are in the 

 process of indirect division. Extending a short distance poste- 

 riorly, the nuclei are found most abundantly in the bounds of 

 the triangle already described. The curves of the U-shaped 

 protoplasmic clouds are also thickly nucleated, as are their ter- 



