138 BOTANICAL GAZETTE . ——_ [aveust 
tissue” at the micropylar end. The result of the growth of the sac is 
seen in the breaking down of the “spongy tissue”; the layers nearest 
the sac are almost used up (a). Seemingly the wall of each cell is 
Ss. 19 
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Fics. 19, 20.—Fig. 19, detail of fig. 18: a, “spongy tissue” broken down; 4 e 
nutritive tissue; 6, compact tissue; c, flattened cells. X930; fig. 20, ovule showing : 
unusual development of “spongy tissue.” “x 37. 
attacked first, probably by an enzyme secreted by the” developins 
gametophyte, and the cells become separated from each other: 
Sometimes a nucleus has its position in an isolated cell, and some: 
times it is surrounded by cytoplasm. The breaking down of this 
tissue resembles that described by CHAMBERLAIN (4) in the formation 
of the pollen chamber of Dioon edule. 
