366 FERNS. 



Pteris aquilina, I have often seen motile spermatozoa 

 in the canal of the opened archegonia, the motion of 

 which spermatozoa ceased during the continuance of 

 my observations. I may add, that these observations 

 were very numerous, and were undertaken with the 

 view of following out the cell-development of the em- 

 bryo. In a single prothallium, cultivated in the 

 manner stated above, and laid open longitudinally as 

 I have mentioned, there will not be found more than 

 three, or at the most four archegonia open at the 

 apex ; spermatozoa will probably be found in not 

 more than one in thirty of such archegonia, and they 

 will often not be found at all."* 



The increase of specimens by means of buds or 

 bulbules must not be confounded with germination. 

 By germination a new generation is produced; the 

 little fern that grows out of the prothallium being the 

 daughter of the plant, whose spore produced that 

 prothallium. The developed bud, however, is but an 

 essential portion of the individual fern on which it 

 grew, and partakes of any accidental (i. e., not speci- 

 fic) peculiarity possessed by it. The production of 

 such adventitious buds is, however, a highly interest- 

 ing phenomenon to the fern-cultivator; especially 

 when they occur upon the leafy part of the frond, as 

 in many species of Asplenium. If we examine one 

 of these proliferous species, A. odontites or A. vivi- 

 parum, for example, we shall see young plants in 

 every stage dotted about on the surface of the fronds, 



* Hofrneister, Higher Cryptoa-, P- 198, note. 



