158 BOTANICAL GAZETTE [SEPTEMBER 
The coenocentrum increases as the receptive papilla decreases; 
either one or the other must be retrograding. From a study of 
these two structures alone it might be difficult to determine the 
true history, but a consideration of the manner in which the 
A. Butiand A. Portulacae. A. Tragopogonts. A. candida. 
Many Many potential and Several poeres and 
functional, functional. one functional. 
NUMBER OF FUNCTIONAL NUCLEI DIMINISHING 
A. Bliti and A. Portulacae. A. Tragopogonis. A. candida. 
Large. Small. Smaller, 
RECEPTIVE PAPILLA DIMINISHING. 
A. Blitiand A. Portulacae. A. Tragopogonis. A, candida. 
as Larger, nutritiv 
Small, Large, nutritive. ren tie ngly pe sn 
COENOCENTRUM ADVANCING IN STRUCTURE AND FUNCTION. 
oosphere of A. Tragopogonis attains the uninucleate condition 
shows that this structure in its ontogeny passes through a stage 
identical with that reached by A. Portulacae and A, Buti in their 
full maturity, thus giving an excellent illustration of the biogenetic 
law. Both the antheridia and oospheres of A. 7ragopogonts are 
multinucleate in their earlier stages, and the development is 
