128 LIVERPOOL BIOLOGICAL SOCIETY. 
escape from the admission of the absolutely universal 
occurrence of cross-fertilization in the Phanerogamia. Every 
Phanerogam is heterosporous, the pollen grain being 
morphologically a microspore, the embryosac a megaspore. 
Vines* in briefly referring to this point postulates the 
necessity for the existence of ‘‘a certain degree of sexual 
affinity between the sexual reproductive cells” and argues 
that “though Phanerogams are strictly speaking dicecious, 
yet they are not so physiologically.” He explains his 
position by assuming that since the sexual generation has 
become rudimentary and merged in the asexual, ‘the 
oosphere and pollen grain stand in the same physiological 
relation to each other as two gametes produced by the 
same plant, a relation which is too close to admit, in 
many cases, of fertile sexual process taking place between 
them.” . 
In criticism of this view it may be said that it is 1m- 
possible to ignore the accumulation of facts brought 
forward of late years in support of the view that so-called 
‘ self-fertilization ” is at least of quite as common occur- 
rence as ‘“cross-fertilization”’ among Phanerogams, and 
that the assumption made by Vines as above quoted 
is too sweeping. Further, it can hardly be said that the 
pollen grain of a Phanerogam is ‘‘ merged in the asexual ”’ 
generation to a greater extent than is the microspore 
in the asexual Selaginella plant. As for the embryosac, 
it is true that the organic connection between that 
structure and the megasporangium (nucellus) is closer 
than that which exists between the megaspore and the 
asexual Selagnella ; still the mere isolation or non-isolation 
of the megaspore in the sporangium can hardly be looked 
upon as having that profound signification by inference 
postulated by Vines. 
*Physiology of Plants, yp. 648, 
