INTRODUCTION. 33 
spermatozoids with a mucilaginous filament contained in or hanging 
from the mouth of the canal of the pistillidium. I have, he 
observes,* seen the spermatozoids swimming in numbers around 
the mouth of the archegonia, but never detected one inside, and I 
do not see any good reason for supposing such a process necessary. 
The pollen-tube of flowering plants only comes in contact with the 
outside of the embryo-sac, and the influence is sometimes com- 
municated through a long suspensor. There does not therefore 
seem to be any sufficient objection to the supposition that the con- 
tact of the spermatozoid with the filament of mucilage which lies 
in the canal of the archegonium, suffices to convey the necessary 
stimulus. 
Notwithstanding some differences in the statements of those 
who, by the aid of the microscope, have investigated this subject 
—differences of no importance in a practical point of view, and 
merely presenting questions of anatomical and morphological interest, 
the balance of the evidence they afford is strongly in favour of the 
view now generally taken, that in this family of plants there are 
organs analogous to the sexual parts of other plants, and that the 
united agency of these parts is necessary to the production of new 
individuals. The whole subject is very amply and lucidly treated 
in Professor Henfrey’s memoir, from which most of the foregoing 
statements are derived, and which, with its accompanying illustra- 
tions, should be consulted by all who take interest in the question. 
After the organisation of a terminal bud within the pistillidium, 
young fronds soon make their appearance. These, at first, are very 
unlike those of the mature plant, being of more simple form and 
more delicate texture, but they gradually acquire more and more 
the characteristics peculiar to their species, though, with the excep- 
tion of a few annual kinds, they are a year or two, or, in many 
cases longer, in arriving at a perfect state. 
* Henfrey, Transactions of Linnean Society of London, xxi. 125. 
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