438 VEGETABLE PHYSIOLOGY 
CHAPTER XXVI 
REPRODUCTION (CONTINUED) 
We have seen that the phenomena of fertilisation are 
preceded in the Phanerogams by an arrangement through 
which the two gametophytes which give rise respectively 
to the male and female sexual cells are developed in such 
close proximity that they ultimately come into contact. 
That which is produced as the result of the germination 
of the microspore or pollen grain, is a tube of varying 
length, which bores its way through the tissue of certain 
parts of the sporophyte, being guided in some manner not 
yet fully understood, until it reaches some part, usually the 
apex, of the megaspore or embryo-sac, in which synchron- 
ously the prothallium which bears the oosphere has been 
developed. In the process of sexual reproduction in these 
plants we have two phenomena presented, which have 
often been treated of as if they were inseparably connected. 
The first of these, which is known as pollination, involves 
merely the transport of the pollen grain to an appropriate 
position on some part of the megasporophyll or of the 
megasporangium itself. The second, which may or may 
not follow the former one, is the actual fusion of the 
gametes which are produced upon the gametophytes to 
which the spores give rise, and which therefore must be 
considerably later in the time of its occurrence. This is 
what we have already described as fertilisation. 
It is necessary to insist on the distinction between 
these two processes, as the phrase ‘the fertilisation of the 
flower’ is frequently somewhat loosely and erroneously 
made use of when pollination is meant. 
We have seen that cross-fertilisation is as a rule more 
