2 52 BOTANICAL GAZETTE [October 



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There can hardly be any doubt that the occurrence of two equal 

 male cells is more primitive, and that any difference in size or 

 loss of function is a more specialized condition. It seems 

 reasonable to suppose that both male cells are functional in all 

 forms which have archegonia collected in a complex, for there is 



nothing to prevent each male cell from reaching an ^g^^ In forms 



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where the male cells are unequal in size the archegonia are scat- 

 tered, thus making it practically impossible for the second male 

 cell to function, and this will of course account for the reduced 



size. 



Three to four pollen tubes appear to be the normal number 

 in Thuja. They either pursue different routes through the 

 nucellus or pass down side by side. In the latter case, one has 

 its tip in advance of the others. In numerous instances it was 

 observed that when the eggs fail to function, as they frequently 

 do, the pollen tube penetrates to the bottom of the complex and 

 in some instances pierces the jacket cells. When this occurs ^ 

 the male cells increase very much in size as the tube nears the 

 bottom of the archegonium complex {^fig^ /). In one instance 

 the cells were 50 ^ in length. The longer diameter of the hemis- 

 pherical male cell at the time of fertilization is in general 20 A^. 



DEVELOPMENT OF THE ARCHEGONIUM. 



Early stages in the development of the endosperm were not 

 studied, but the process seems to be similar to that described 

 by Jager (9) for Taxus. 



The archegonium initials are differentiated about the middle 

 of June, their number being usually six. They rapidly elongate, 

 become conical, and as yet have very little cytoplasm {fig- ^\ 

 The nuclei move toward the outer end of the initials and the 

 neck cells are cut off {fig, p). So far as could be determined 

 they are cut off simultaneously. Each neck cell divides by 

 anticlinal walls, forming from two to six cells, and there is no 

 periclinal division. Almost immediately after the last antichnal 

 wall is formed the neck cells begin to disorganize, and they are 

 soon almost entirely assimilated by the central cells, which at 

 this time are increasing in volume at a very rapid rate. 



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