On Azolla and Salvinia. 243 



the appearance of the grains within the ovulum, and on the 

 subsequent new growths presumably excited into action 

 thereby, and their direction, which proceeds from the point 

 next the point of application of the supposed fecundating in- 

 fluence.* 



I am not willing to omit an analogy with Phanerogamic 

 fecundation derived from the apparent inaptitude of the 

 means to the end. It has always appeared to me remark- 

 able by what means a tube of such tenuity, of such flexibility, 

 and with such an obtuse point as a pollen tube can not only 

 get at the nucleus, but overcome the resistance presented by 

 its solid tissue so far as to penetrate it to a certain, and 

 often not inconsiderable a distance. Of this apparent insuf- 

 ficiency Azolla has a considerable share ; yet the access of 

 the grains to the inside of the ovulum appears certain. 



Difficulties however are at present offered by both genera. 

 In Salvinia there are three kinds of bodies, which might be 



* Assuming fecundation to take place in Azolla and Salvinia, there will be, I 

 think, three modifications at least of this phenomenon among the higher acotyle- 

 donous plants. In one the male influence is applied to the apex of the pistillum, 

 in the second to the nucleus without the intervention of a pistillary apparatus. 

 In the third the male influence is exerted on the frond itself, and is followed 

 by the development of the young capsule from a point in the substance of the 

 frond corresponding to and sometimes distant from the place to which the male 

 influence has been applied. 



This is founded on observations made on Anthoceros in 1836, from which it would 

 appear that the place of exsertion of the future capsules is pointed out by a slight 

 protuberance, over the apex of which a flake of matter like the male matter of Musci 

 and Salvinia is spread, sending down to some distance within the frond a tube-like 

 process, which causes the dislocation of the cells of the tissue with which it comes 

 into contact. 



The future capsule is stated in my notes not to be appreciably pre-existent, and its 

 situation, which is exactly under the line of direction of the descending process, 

 above mentioned, is only pointed out by a bulbiform condensation of the tissue of the 

 frond. The young capsule during its development ascends along the same line, 

 and pushes before it a corresponding cylindrical body of the tissue of the from!, the 

 calyptra of authors. 



I have never since had an opportunity of verifying these observations which, if 

 correct, may I think prove of some importance. 



