34 BOTANICAL GAZETTE [july 



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1910. 



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1. Newman, R., tJber die Entwicklungsgeschichte der Aecidien und Spermo- 

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The relationships of the aecidium cup type of rust. Science 27:213-215 

 1908. 



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1910. 



25. , Nuclear conditions in certain short-cycled rusts. Science 33 :I 94 



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Proc. Amer 



EXPLANATION OF PLATES I AND II 



All of the figures were drawn with the aid of the camera lucida, and, except 

 where otherwise mentioned, at a magnification of 1140 diameters. They are 

 all placed in their natural position in the sorus, with the top of the page repre- 

 senting the direction of the leaf epidermis. 



Puccinia Claytoniata 



Fig. 1. — A section through the lateral border of the cup before the cell 

 fusions; 6 layers of encircling hyphae are seen at the top, below these are the 

 sterile cells of the pseudoparenchyma and below these the perpendicular 



hyph 



X57°- 



— — — — f v r 



Fig. 2. — A more highly magnified view of the tip of a gametophoric hypha 

 in a young aecidium; the nucleus of the apical cell is shown in the anaphase of 



mitosis. 



Fig. 3. — An earlier stage of mitosis in a uninucleated cell. 



