GERM CELLS AND THEIR FORMATION 



91 



protoplasm, or by the collection of various pigments and dif- 

 ferently colored granules, or by forms 

 of deutoplasmic materials other than 

 yolk, or in various other ways. The 

 disposition of these substances usu- 

 ally expresses, incompletely, how- 

 ever, an underlying organization or 

 morphology of the egg substance as ,. 

 a whole, which is considered a fun- 

 damental structure of the egg as a 

 specific organism. This organiza- 

 tion is practically always polar, i.e., 

 disposed symmetrically with refer- 

 ence to one chief axis (Von Baer), 

 and in the eggs of most bilateral d 

 animals examined, it is bilateral also 

 (Roux, Van Beneden). In some 

 Iway this morphology of the egg is 

 related to the morphology of the 

 embryo developed from the egg, and 

 hence is called its promorphology. 



This promorphology is better 

 termed organization, for it is not only 

 grossly material, but also dynamic, 

 i.e., energetic, depending upon chem- 

 ical and physical arrangements not 



often visible directly. The extent drawing of a median section 



and nature of this organization are 



FIG. 47. Semidiagrammatic 



Often Obscure, but this, and the and Heider, after Henking and 



, Blochmann. en, chonon; d, 



nuclear Structure OI the OVUm, are flattened dorsal side of the egg; 



probably its most important char- 



acteristicS, for together these deter- truded through themicropyle; 



,, . . , , A;, cortical layer; m, micropyle; 



mine the COUrse Of its development this also marks the anterior end 



as a specific creature. of " e : ?> e ^ a d ?P erm 



. . t pronuclei in process of fusion; r, 



Polarity is One expression Of this polar bodies; v, ventral side of 



organization. The polarity of the egg ' 



fully formed ovum is related to the polarity of the egg cell 



