80 MARGARET C. FERGUSON 



are not rare. Campbell ('oo) has recorded such a condition in 

 the Aracece, Lloyd ('01) in certain Rubiacea, and Karsten ('02) 

 in the Juglandacecz. But, so far as investigated, the sequence 

 of events following the establishment of the axial row in the 

 Abietinece. results in the obliteration of all but the lowest cell. 

 I have avoided using the term " potential macrospore " in con- 

 nection with the upper cells of the axial row, because the upper 

 of the two cells first formed does not always divide and in such 

 instances it cannot properly be designated as a spore since 

 development ceased before spore formation was completed. 



Growth of the Macrospore. Starch is sometimes found 

 within the cells of the axial row, though never in such abundance 

 as in the cells of the adjacent tissue (fig. 143). It may become 

 very abundant within the macrospore during its period of growth, 

 and is sometimes found pressed so closely against the nucleus 

 as to actually produce indentations in its membrane (fig. 146). 



The reticulum of the nucleus of the functional spore is very 

 scanty during its growth period, but later it presents the appear- 

 ance of an ordinary resting nucleus. The cytoplasm, never 

 abundant, forms at an early date a loose, granular network. 

 Later the nucleus is connected with the ectoplasm by delicate 

 strands which are gradually withdrawn into the peripheral cyto- 

 plasm, until there is thus formed in the one-celled stage a 

 definite layer of cytoplasm lining the wall of the macrospore, 

 and inclosing a large central vacuole. The nucleus moves to 

 one side of the cell, usually the upper side, imbeds itself in the 

 cytoplasm and awaits further development (figs. 147, 148). 



The organization at so early a period of this definite peripheral 

 layer of cytoplasm has not, I believe, been demonstrated for 

 any of the other Gymnosperms. Finding the cavity containing 

 the developing endosperm crossed by irregular strands of cyto- 

 plasm as illustrated in fig. 70, plate VI, I had the impression 

 for a long time after these studies were begun, as stated in an 

 earlier paper (ipoi 3 ), that such a condition, as that described 

 above for the resting macrospore, did not obtain until the 

 beginning of the second period of growth. This layer of cyto- 

 plasm is very easily displaced by the action of the fixing fluid, 

 but with care it may be obtained in an apparently normal con- 



