NO. 1431. BREEDING HABITS AXD EGG OF PIPEFTfiTI—GJDGER. 487 



like tig'. 65. Some of the outer cells show a teiideney to elongate and 

 are somewhat smaller than the interior ones. Both marginal pads 

 are nucleated, and in one a cell wall is cutting downward. While the 

 peril)last has cells resting on it and even depressing it, nowhere in the 

 blastoderm is there any evidence that they have been budded oli'. 



ST.\GE WITH KIVE-HUNDRED-TWEI.VE CELLS ON THE SURFACE. 



Fig. 71, the normal type, is very similar to the preceding figure. 

 Here the cells are pretty uniform in size, and those on the surface are 

 noticeably elongated, some being di-awn out in tine thread-like con- 

 nections — the beginning of the ^''DeckscJuc/if^ of the Germans. kSome 

 of the nuclei are in process of division by mitosis, but the majority 

 stain solidly. The outer thickenings of the periblast are nucleated, 

 the ba.sal portion is thin, yolky, and totally devoid of either nuclei or 

 cells. 



The rounded type is finely shown in fig. 72. The surface cells are 

 slightly flattened and only occasionally pointed, and one on the right 

 is l)inucleate. The blastomeres are by no means uniform in size, and 

 on the right is a giant cell with a proportionate nucleus. All the 

 nuclei stain solidly. The periblast is very thick, and, while laden with 

 3'olk fragments, is fairly distinct below. There are two nuclei in the 

 periblast. One is in a thickening out of which a cell will probably be 

 formed. Near })y are cells which seem to have been recently cut out. 



Fig. 73 is an excellent illustration of the flat type. The blastomeres 

 are very uniform in size and distribution, and are especially notewor- 

 thy for the large number of dividing nuclei, with spindles at all angles. 

 The chief interest, however, centers in the periblast, which is thick 

 and possesses many yolk granules, but is perfectly distinct. In it to 

 the right is a nucleus dividing by mitosis with a spindle considerably 

 longer than those in the blastomeres. On the left the section cuts 

 through a chromatin bundle at right angles to the spindle. At the 

 extreme left is found, for the first time, a nucleus in the outer peri- 

 blast. The central periblast in this blastoderm is very rich in nuclei 

 dividing by mitosis. A cursor}^ examination showed one vertical and 

 eight horizontal ones. Another blastoderm, of the same lot and 

 stage, contains, in its periblast, thirty-three oblique spindles at all 

 angles from nearl}- vertical to nearly horizontal, twenty -nine lying 

 horizontally, and seven standing in a vertical position. In all, sixty- 

 nine spindles were counted (none twice). There are a very few solidly 

 staining nuclei, but a great number are cut, as above, through the 

 chromatin masses, and these are not counted. There can l)e no doubt 

 that the spindles stand in all positions. 



The last type of this stage is tig. 74. The cells are not uniform in 

 size, and many are twice as large as the small ones. Most of the 

 nuclei stain solidly, but some contain spindles. Two binucleate cells 



