﻿1903] 



BRIEFER ARTICLES 



213 



a mucilaginous secretion a short time before fertilization occurs. 

 The secretion passes outward in the cavity surrounding the macro- 

 sporangia, often forming a hood around each macrosporangium 

 {fis- j)- In passing the mlcropyle the secretion often finds its way 

 into it, and may force its way for some distance between the inner 

 and the outer integuments. The 

 question arises: Is not this an 



ar///i7^/, caused by some fault in the 

 technique? The methods of prepar- 



ing 



the material were varied until 

 there was no longer any doubt as 

 to their reliability and the identity of 

 the secretion whenever obtained. A 



somewhat similar 



thing 



has been 



noted by Guignard (10) in the tulip. 

 He speaks of papillae lining the 

 wall of the cavity surrounding the 

 niacrosporangia, among which the 

 pollen tube makes its way to the 

 micropyle. Campbell also mentions 

 the presence of secreting cells on the 

 funiculus in Naias, but found no 

 secretion. Wherever I have seen 



fi 



Fig. 5, — A macrosporangium at the 



pollen tubes in my sections they ^;^^ ^f'f^rtjji.^tion: .5, haustorial tube; 

 have been growing in or toward this s, secretion from placentae. X 270. 

 secretion. There is no evidence 



that this secretion has any distinctively nutritive function in itself, 

 but rather that it serves as a medium through which the substance 

 capable of attracting pollen tubes diffuses outward from the micro- 

 Pyle. If the colloidal secretion were nutritive, there would be an 

 attraction of the pollen tubes into all parts of the secretion, but this 

 is not the case. 



The t^g cell of the embryo-sac is fertilized shortly after the forma- 

 tion of the secretion. The results of fertilization are several: the 

 formation of the secretion from the placentae ceases and all which 

 exists disappears; the small rectangular cells on either side of the 

 haustorial tube rapidly elongate, and the embryo sac enlarges in a 

 transverse direction.— Howard S. Reed, University of Michigan. 



LITERATURE CITED. 

 I. Strasburger, E., Die Angiospermen und die Gymnospermen. Jena. 



1879- 



