CONIFERX. 
5' 5 
is developed from a group of superficial cells : these multiply by repeated division, 
so that a protuberance is formed consisting of a number of rows of cells invested 
by a parietal layer : the terminal cell of the lowest of these rows becomes the 
archesporium, and it is therefore, in this case also, a hypodermal cell. The cells 
of the tapetum are derived entirely from the parietal cells of the pollen-sac, just 
as is the case in the sporangium of Lycopodiiwi. Goebel draws attention to the 
fact that in the majority of the Cupressinese the pollen-sacs are protected by an 
outgrowth of the staminal leaf which he considers to be analogous to the indusium 
of Ferns.] 
A formation of cells, recalling the rudimentary development of a prothallium 
in the microspores of Selaginella and Isoetes, takes place in the pollen-grains of 
the Coniferae before their dissemination, in the same manner as in those of the 
Cycadese (compare Fig. 345). The process is a very simple one in Taxus 
Podocarpus, the Cupressineae, Araucaria and in the true Pines. The contents of 
the pollen-grain are divided by a septum so as to form a large and a small cell, 
the latter undergoing no subsequent change (Fig. 351). In the other Abietinea? 
the septum becomes arched into the cavity of the larger cell, and a second septum 
is formed in the smaller cell, so that a two-celled body is formed which is situated, 
as in the Cycadeae, at the posterior end of the grain. At this point the extine 
presents a split which was formerly regarded by Schacht as being the basal cell 
of the internal group, but which, according to Strasburger, arises in the same 
way as the vesicular expansions of the extine found in the grains of many species 
of Pinus. Strasburger has shown that in all cases it is the large cell of the 
pollen-grain which grows out into the pollen-tube, as is the case in Cycadese 
(Fig. 345). If we pursue the comparison with the highest Cryptogams which 
has been already initiated, we must regard the pollen-tube as representing the 
antheridium to some extent, and the internal group of cells, formed before the 
development of the pollen-tube, as corresponding to the vegetative cell in the 
microspore of the Ligulatae, for, like it, it undergoes no subsequent change. A 
peculiarity which distinguishes the pollen-grain of Conifers from that of Angiosperms 
lies in the rupture and final stripping off of the extine by the swelling of the 
intine (Fig. 351, /, //, ///). Even in this apparently insignificant fact a resem- 
blance is again seen to the microspores of Cryptogams, and especially to those of 
Marsiliaceae, in which the swelling endospore protrudes through the exospore. 
The structure of the Female Flowers is very different in the different sections of 
Coniferae, and in some cases the homology of the separate parts is still doubtful. 
The position of the ovules, as far as can be judged from advanced stages of develop- 
ment, is, in particular, very variable, and with this is again connected the fact that 
different opinions may be entertained as to the part which should be called the 
carpel. The following description of these structures, a full discussion of which is 
not permitted by our limited space, is drawn immediately from the observation of 
advanced stages of development ; it is possible, however, that the direct observations 
of the most rudimentary stage will cause an alteration in some points ^ 
The female flowers of Taxus spring from the axils of foliage-leaves belonging 
' Compare Strasburger and Eichler, loc. cit. 
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