268 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 2 



Professor F. E. Lloyd, of McGill University, who kindly 

 came to my aid in this matter, now made a brief study of the 

 intra-vitam staining in the ovules of Scrophularia and found 

 that the reagent accumulated throughout the embryo-sac in- 

 clusive of the egg cell, demonstrating the possibility of the 

 direct action of introduced solutions on the entire egg appa- 

 ratus as well as upon the endosperm. The micropylar orifice 

 was closed and was not stained in the ordinary treatments and 

 took up only a small amount of the dye when laid separately 

 in a solution of it. Professor Lloyd also showed me prepara- 

 tions in which pollen tubes deeply stained had entered the 

 micropyle and had elongated, reaching the egg. 1 These experi- 

 ments made clear the immediate possibility of reagents reach- 

 ing the egg apparatus through the funicle and of the staining 

 of the pollen tube and nucleus in the cavity of the ovary before 

 fertilization. It is also possible that the pollen tube might 

 be affected by reagents which had accumulated in cells through 

 which it penetrates to the egg nucleus (fig. 4). 



These facts would make it probable that treatments before 

 pollination has taken place would affect the embryo-sac and 

 its inclusions only, while introductions of solutions at a later 

 stage would be likely to affect the pollen tubes and nuclei. 

 These generalizations are to be taken to be applicable to Scro- 

 phularia, and to species which present similar arrangements 

 for reproduction. The egg in ovules in which the micropyle is 

 open might be even more readily exposed to the action of a 

 reagent, and if the ovule is porogamous the pollen tube would 

 also inevitably be affected, and still many other combinations 



may be encountered which need not be enumerated at this 

 time. 



It is of course to be understood also that not all of the ovules 

 in any pistil are in equivalent stages of development at any 

 given moment, and this applies also to the penetration by the 

 pollen tubes. Pollination of Scrophularia takes place in the 

 morning, and substances introduced before mid-forenoon 



1 See Lloyd, F. E. The intra-vitam absorption of methylene blue in ovules of 

 Scrophularia. Report of the department of botanical research for 1914. Carnegie 

 Inst. Washington, Yearbook 13:77-81. 1914. 



