DEPARTMENT OF BOTANICAL RESEARCH. 79 



for about 12 hours, when the selective behavior of the tissues was 

 revealed in the clearest manner. In this way it was seen that a trans- 

 verse zone of tapetal cells (about six cells broad and removed from the 

 antipodal end of the embryo-sac by another zone of equal extent) is very 

 avid of the stain and shows deep coloration, though at the time the 

 endosperm cytoplasm may show none. The micropyle and the tissues 

 surrounding it display under similar conditions no smallest trace of the 

 stain, and progressive staining shows that the stain passes from the 

 chalaza onwards toward the micropyle and not in the reverse direction. 

 The pollen-tubes, however, take up the stain abundantly, and this cyto- 

 plasm m.ay be followed with great ease through the micropyle as far 

 as the egg-apparatus. 



The above facts indicate with a fair degree of certainty the following 

 conclusions : 



(1) When a reagent such as methylene blue is placed within the 

 ovarial cavity it can reach the egg-apparatus by way of the funicle, 

 nucellus, and embryo-sac; the walls of the nucellar cells present a 

 chemical structure which enables them to absorb methylene blue, in 

 contrast to the remaining cell-walls of the ovule. I judge them to be 

 somewhat hydrolyzed. 



(2) A restricted zone of the tapetum, as above delimited, has a 

 special function, as evidenced by the very great staining of the pro- 

 toplasm of its cells. It would seem, however, in view of the appearance 

 of o\ailes subjected to intra-ovarial staining for 2 days, that for the 

 transfer of the stain the tapetum is of less importance than the nucellus. 

 This inference, based on the relative depth of the stain, may not allow 

 any conclusions as to the relative physiological importance of the 

 tapetum. 



(3) If ovaries are injected a few hours after pollination, the reagent 

 may reach the male nuclei and their cytoplasm, and, through the pollen 

 tubes, the egg-apparatus. 



(4) The reagent probably reaches the egg-apparatus much more 

 quickly than a visible accumulation of the stain would indicate. 



Alterations Induced hy Ovarial Treatments of Plants, hy D. T. MacDougal. 



The fact that seeds matured in ovaries of Scrophidaria, which had 

 been treated with a dilute solution of potassium iodide, produced two 

 aberrant individuals was noted in the report for 1913. The further 

 cultivation of these perennial plants, and of the second generation, 

 makes possible the following tentative conclusions : 



(1) The introduction of solutions into the ovaries of Scrophularia 

 may result in affecting the embryo-sac or pollen-tube singly or simul- 

 taneously, or the fertilized egg. (See Lloyd, p. 77.) 



(2) The effect of the reagent in changing the egg or pollen nucleus 

 separately would lead to the formation of a hybrid by the union of a 

 normal and an altered element. 



