373 
Bower . — A Criticism , and a 
possibility, and certainly does not justify the statement that 
it cannot occur. 
The suggestions which I have offered in my studies on 
spore-bearing members involve the thesis that there are 
potentialities of elaboration of such parts as we style sporangia, 
analogous to the potentialities of axis, leaf, root or hair. 
Every one of these parts is susceptible of variations in size, 
form, and structure, in different plants, while all may be 
branched : in certain species, genera, or even families, the 
branching of any of these parts may, it is true, be in abeyance ; 
but speaking of these parts generally, the potentiality of 
branching is one of their characters. What good reason is 
there for assuming that sporangia have not this potentiality, 
and thus differ from all other parts of the sporophyte? 
In point of structure great fluctuations are seen in axes and 
leaves, or their parts : vascular tissues, habitually present, 
may be entirely absent in certain cases, while the morpho- 
logical character of the part is not considered to be thereby 
affected. Conversely, emergences, which are commonly 
without vascular supply, are in some cases traversed by 
vascular bundles ; but they are not by reason of this elevated 
to a higher morphological category. Accordingly, the presence 
or absence of vascular bundles in a given part need not affect 
our view of its sporangial character: it is to be noted that 
though vascular tissue is usually absent from sporangia, it is 
present in the ovules of Phanerogams, which are generally 
admitted to be sporangia. 
With regard to branching also a similar line of argument 
may be used, and it may be pointed out as against the fact 
that branching of sporangia is not generally recognized, that 
branched sporangia do occur in Salvinia natans : while the 
megasporangia of this species are attached by separate stalks, 
the microsporangia, otherwise similar as regards position, are 
borne on repeatedly branched pedicels. I have not yet worked 
out the details of development of this interesting case, but 
a good representation of an advanced stage is given in 
Rabenhorst’s Kryptogamen Flora, vol. iii. p. 603. 
