IX) 



FORMATION OF POLAR GLOBULES. 



B C 



Fig. 9. FORMATION OP THE FIRST POLAR GLOBULE IN THE EGG OF ASCARIS MEGALOCKPHALA. 



(v. Gehuchten. ) 



A. The ovum with the germinal vesicle transformed into a spindle of (achromatic) fibrils ' from the 

 poles of the spindle other fibrils i-adiate into the protoplasm. At the equator of the spindle eight 

 portions of chromatin are visible ; cs, head of a spermatozoon which has previously entered the ovum, 

 and is becoming transformed into the male pro-nucleus ; m, gelatinous membrane of the ovum. 



B. The chromatin particles are seen separated into two sets. The achromatic fibrils are not shown 

 in this preparation. The ovum is considerably shrunken. 



C. Half of the germinal vesicle is extruded into a perivitelline space, and along with a portion of 

 protoplasm is becoming separated off from the ovum as a polar globule. The extruded half includes 

 four of the chromatin particles ; the other four remain in the ovum ; m', membrane dividing the polar 

 globule from the ovum. 



Fig. 10. FORMATION OF THE SECOND POLAR GLOBULE 



IN ASCARIS MEGALOCEPHALA. (Camoy.) 



A. The remainder of the germinal vesicle (after 

 extrusion of the first globule, y l ) has again become 

 transformed into a spindle of achromatic fibrils, 

 with the four remaining chromatin particles at the 

 equator of the spindle. 



B. The spindle, now irregularly Y-shaped, is seen 

 approaching the surface of the ovum ; g l , first polar 

 globule ; ns, male pronucleus which has become 

 formed from a spermatozoon. 



C. Extrusion of half of the germinal vesicle 

 remainder. 



D. Completion of the process ; the secr.nd polar globule, y", is now separated from the ovum ; ii 

 contains two of the chromatin particles. The other two remain in what is left of the germinal vesicle, 

 n >{ which now forms the female pronucleus ; ns, male pronucleus ; g l , first polar globule. 



