Eugene Howard Harper 381 



more than one male nucleus has been found in very close proximity to 

 the egg nucleus. 



3. The stage of development of the egg may be approximately inferred 

 from its position in the oviduct. The first polar spindle is formed in the 

 ovarian egg. The first cleavage occurs about the time the egg is entering 

 the shell-gland. The time elapsing between impregnation and the first 

 <;leavage is apparently between two and three hours. 



4. The polar bodies lie within the egg membrane, in a depression in 

 the cytoplasm. The second disintegrates before the first, showing a 

 tendency to form a network and become metabolic like the egg nucleus. 



5. There is an area of active protoplasm surrounding the nucleus 

 which during the maturation stages is oriented as a cone with the spindle 

 at its apex, from which the polar bodies are pinched off. In preparation 

 for cleavage, this area becomes oriented horizontally in the germinal 

 disc. It undergoes amoeboid changes and displays a differentiation into 

 an outer hyaloplasmic and an inner granular area. It elongates in the 

 direction of nuclear division, and divides with the division of the nucleus. 

 The appearance of amoeboid movements dies out during the resting period 

 ■of the nucleus, and reappears at the second division. One blastomere is 

 more hyaloplasmic than the other, and shows more complex amoeboid 

 ■changes. 



6. The supernumerary sperms which enter the egg pass from the 

 point of entrance toward the periphery of the disc. The accessory nuclei 

 undergo division earlier than the cleavage nucleus. At the margin of 

 the inner disc they come to rest within the coarser granular material, and 

 give rise to an accessory cleavage on the surface of the disc. They divide 

 niitotically without abnormalities, so far as discovered at this stage. 

 They contain the reduced number of chromosomes, which is eight. The 

 chromosomes differ in shape from those of the cleavage nuclei and the 

 maturation spindles, being more slender. In late cleavage these nuclei 

 are found outside the blastoderm, at or near the margins, and dividing 

 amitotically. Some traces of abnormal mitosis were found. 



7. Asters and centrosomes were found in the maturation stages, though 

 not conspicuously developed. There is a progressive increase in the 

 distinctness of these structures as the nuclei become limited to narrower 

 areas by cell division, so as to become surrounded by the more plastic 

 •C3d:oplasm resulting from their activity in altering the yolk. The less 

 pronounced development of these structures in the maturation and early 

 cleavage stages seems due to the nature of the cytoplasmic groundwork, 

 as well as to the casual interference of yolk granules. The sperm nuclei 

 likewise do not display well developed achromatic structures till they are 



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