V. 



Recent Observations on Fertilisation and 

 Hybriclity in Plants. 



THE object of the following paper is to bring before the readers of 

 Natural Science the most recent results which have been 

 attained by workers in that department of Plant Physiology which 

 relates to the actual process of the fertilisation of the female by 

 the male element, and of the secondary processes by which the access of 

 the active to the passive element is assisted. The enquiry naturally 

 divides itself into two branches : (i) The nature of the process itself ; 

 (2) The subsidiary phenomena. The first of these enquiries evidently 

 goes to the foundation of the laws on which depends the succession of 

 life on the earth. Observations on this head, to have any value, 

 must be carried out by experts of great knowledge, and with trained 

 skill in the use of the most delicate microscopical appliances ; the 

 lowest forms of life, as well as the highest, must be put under requi- 

 sition to yield up their secrets. As we ascend in the scale of 

 organised beings, the various vital processes become more compli- 

 cated, and secondary phenomena play a larger pare in them ; and it 

 is in Flowering Plants that these become most interesting and most 

 within the scope of the non-scientific observer. As, therefore, this 

 will be the most familiar branch of the subject to those of our readers 

 who have not made the physiology of plants their special study, we 

 propose to commence with it. 



The process by which the ovule of Flowering Plants is fertilised 

 by the pollen-grain — i.e., is acted on so as to be enabled to produce an 

 embryo, without which no seed can germinate — is sufficiently 

 well-known. The pollen-grain (the male element) must first 

 be deposited on the stigma, where it puts out a pollen- 

 tube which penetrates into the embryo-sac of the ovule, and 

 there, coming into contact with one of the embryonic vesicles (the 

 female element) fertilises it, the result being the growth of the 

 embryo within the embryo-sac. The subsidiary phenomena are here 

 the conveyance of the pollen-grain to the stigma, and the entrance of 

 the pollen-tube into the embryo-sac. In the last-named process a 

 great uniformity prevails throughout the Angiosperms or larger 

 section of Flowering Plants ; the only important exception being the 



