Centrifugal Force upon Beetles^ E,ggs 519 



more of the large yolk-globules near the outer end and less of them 

 at the other pole. There is also a slight thickening of the ''Keim- 

 hautblastem" at the sides of the egg near the inner end. The 

 pole-disc is present in its usual position, but it is surrounded 

 by a greater number and larger, irregular vesicles than in C. B. 

 4, h. 



C.B. ./, d. An egg taken from the centrifugal machine at 

 the end of an hour is definitely stratified, two distinct layers being 

 visible. There is a small cap of orange-colored material situated 

 at the extreme inner end, v^hile the rest of the egg representing the 

 other layer has changed in color because of the redistribution of the 

 yolk. The intense yellow color of the outer end is dup to the 

 invasion of a vast number of large deutoplasmic spheres into that 

 region. No definite layers can be distinguished in this large por- 

 tion, since the change in color from bright yellow at the outer end 

 to pale yellow at the inner end is gradual. A longitudinal section 

 through this egg is shown in Fig. 10. Most of the large yolk- 

 globules lie in the outer region; the interdeutoplasmic spaces are 

 entirely free from the cytoplasm which usually fills them. The 

 " Keimhautblastem" has been forced almost entirely away from 

 the outer end and from the periphery of the outer third of the egg 

 and has added its mass to that of the inner region. At the extreme 

 inner end one large, bud-like protrusion (one-third the short 

 diameter of the egg) and several smaller ones have formed. They 

 are covered externally by a thin layer of ''Keimhautblastem" and 

 are composed of a great number of vesicles. A similar vesicular 

 portion was noted in the two eggs described above (C.B. 4, b and 

 c), but it has in this egg reached such proportions that we shall 

 hereafter call it the vesicular zone. This is the material which 

 appeared bright orange in color in the living centrifuged egg. 

 Only one nucleus could be discovered in the entire egg. This is 

 situated at one side near the inner end, as shown in Fig. 10, n. 

 The pole-disc has moved from its position at the end and has 

 traveled en masse away from the axis of rotation. It has carried 

 that portion of the " Keimhautblastem" in which it is suspended 

 along with it, producing a distinct depression at one side of the inner 

 end of the egg. The sections containing the pole-disc fell outside 



