274 



THE AMERICAN NATURALIST 



[Vol. XL 



nuclei found by Juranyi (72) in the young pollen tube of Cerato- 

 zamia longijolia and by Arnoldi ( : 00) in Cephalotaxus fortunei 

 represent two cells in the antheridium wall or tube cell of the pollen 

 grain, but that interpretation can hardly be insisted upon very 

 strongly on the evidence now available. 



In the case of the two or more tube nuclei in the pollen tube 

 of angiosperms, the above interpretation ought to be considered, 

 but here there will be even more hesitation over its acceptance 

 than in the gymnosperms. 



As regards the large number of nuclei found in the pollen tube 

 of Agathis and Araucaria, Lopriori concludes that in Araucaria 

 hidwellii they are male nuclei, and that the cell-complex which is 

 formed in the pollen tube, and from which they are derived, is a 

 spermatogenous cell-complex. Lopriori's conclusion is evidently 

 much influenced by Juel's discovery of the numerous male cells 

 in Cupressus. The present writer cannot accept Lopriori's con- 

 clusion until there is direct evidence that the nuclei in question 

 do actually function in fertilization. The reasons for rejecting^ 

 the conclusion at the present time are these : — 



1. The cell-complex from which the nuclei are derived is formed 

 in the pollen grainjand not in the pollen tube as Juel found in 

 Cupressus goweniana. 



2. It is formed, not from a single generative cell, but primarily 

 by the successive unequal divisions of the large cell of the pollen 

 grain, though secondarily the small cells,thus formed may them- 

 selves divide in different directions. 



not spermatogenous in its nature, but that it is the vegetative part 

 of a male gametophyte, and as such is exactly the condition which 

 the present writer thought he had found when he first saw tlie 

 |)olIeii grain of Picea represented in Fig. 10 (1*1. I). Tliough this 



it is to be hoped that these investigators will follow out the full 

 life history of all the cells and nuclei found in the pollen grain and 

 tube of the Araucarineae. 



