181* 



ANDROGENES IS 



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POLAR BODY FORMATION: RANA PIPIENS 



(From Porter, 1959: Biol. Bull. 77:235) 



Figs. 1-4. Semi-diagrammatic representations of four sta^^es in second polar body forma- 

 tion of R. plpiens eggs. Drawings were made with camera lucida and give ex- 

 act distribution of pigment granules, yolk platelets and cliromosomes, only 

 part of which are shown. Selected from considerable material sectioned at 

 10 )i. (Eggs inseminated and kept at 12°C.) 1125 X. 



Fig. 1. Division spindle as in egg at time of insemination. 



Fig. 2. Anaphase of maturation division. Stage at which spindle can be seen from ex- 

 terior of egg as small black dot. Egg fixed 35 minutes after insemination. 



Fig. 3. Early telophase. Egg fixed 50 minutes after insemination. 



Fig. 4. Polar body just forming. Egg fixed 56 minutes after insemination. 



BEFERENCES : 



Baitzer, F. & V. de Eoche, I956 - "Uber die Entwlcklungsfahigkelt haploiden Triton al- 

 peatria." Eev. Suisse de Zool. k^-.k'^'^. 



Eaat, E. M., 19514- - "The nucleus-plasma problem," Am. Nat. 68:289 & k02. 



Fankhauaer, G. & C. Moore, 19^1 - "Cytological and experimental studies of polyspermy in 

 the newt, Triturus viridescens. II. The "behavior of the sperm nuclei in androgene- 

 tic egga (in the absence of the egg nucleus)." Jour. Morph. 68:387. 



Kaylor, C. T., 19'*-1 - "Studies in experimental haploidy in salamander larvae. II. Cyto- 

 logical studies on androgenetic eggs of Triturus viridescens." Biol. Bull. 81:14-02. 



Porter, K. R., I9UI - "Diploid and androgenetic haploid hybridization between two forms 

 of Bana pipiens Schreiber." Biol. Bull. 80:238. 



"How it chanced that a man who reasoned upon his premises 

 so ably should assume his premises so foolishly is one of the 

 great mysteries of human nature. " 



MacAul ey to Dr. Johnson 



"It IS this t hought- transmi t t in^ prepotency of the human 

 species, more than any other, that gives it a superlative lead 

 over all the creatures of the globe." 



A. J. I.otka 1925 



