1915] 



MACDOUOAL — MODIFICATION OF GERM-PLASM 



269 



would be taken up and diffused through the tissues, especially 

 through the funicle before the pollen tubes had reached the 

 cavity of the ovary. Introductions timed to meet the elongat- 



mic- 



'otsum 



Fig. 4. Diagram of longitudinal section of ovule of 8 crophularia : fun, funicle; 

 chal, chalaza; ant, antipodal cells; tap, tapetum; end, endosperm; mic, micro- 

 pyle. The shading shows the course of a solution of methylene blue diffusing 

 through the funicle from the placenta (see fig. 3) and its selective fixation in 

 the tapetum and nucellus. The solution finally reaches the ovum. 



ing pollen tubes would of course be more liable to affect the 

 pollen nuclei, and a number of lots of seeds matured in ovaries 



