106 Henderson — Comparative Study of Pyrolaceae and 



with parietal placentae, the increase in the number of seeds 

 and the reduction in their size and in the number of cells of 

 the endosperm and embryo. The writer has traced such a 

 gradual transition in structure from the simplest group of the 

 Ericaceae, i.e., the Rhododendroideae-Ledeae, through the 

 slightly saprophytic Pyrolaceae to the completely saprophytic 

 Monotropaceae. The genera Pterospora and Sarcodes seem in 

 their characters to be different from the others, as if these two 

 had arisen in a different line, perhaps from some of the higher 

 members of the Ericaceae with campanulate or urceolate corollas. 

 On account of the lack of distinct differences and the numer- 

 ous resemblances and intergrading characters between the more 

 primitive Ericaceae, the Pyrolaceae, and the Monotropaceae, 

 the writer concludes that the last two should be considered as 

 sub-families under the Ericaceae. 



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