812 • REPORT- -1902. 



If these plants had grown on the spot where we now find them, and been 

 petrified, we should have certainly found, where we had an abundance of nodules, 

 that these stems would have been continued from nodule to nodule ; but that is 

 not so. What we find is a quantity of iragments of short pieces of stems, &c., 

 some with the cortex, some without, some split in fragments, and so on. The 

 natural conclusion is that the various portions of plants have been carried into 

 their present position after being broken in fragments, and before petrification, or 

 they have been carried from a parent bed after petrification. 



8. The Morphology of Sjwrangial Integuments. 



By W. C. WORSDELL. 



Aiigiosperms. 

 Theories on the nature of the integuments of the ovule: — 



1. FoHar-appoidcif/e theory : The integuments are the foliar appendages of the 

 imcellns, which is a stem structure. Supporters of this view : Alex. Braun, Aug. 

 St. Hilaire, Schleiden, Payer, Schmitz. 



2. Sui (jeneris theory : The integuments are special protective outgrowths of the 

 sporangium, this latter being an organ mi generis. Evidence for this view is 

 afforded solely by facts of ontogeny : Slrasburger, Goebel, Eichler. 



3. Foliolar theory, chiefly elaborated by the last of the undermentioned authors. 

 Based entirely on the evidence of the abnormal metamorphoses of the ovule ; these 

 are of a very constant character, subject to control of very definite laws ; the two 

 integuments tend to proliferate into a three-lobed marginal leaflet or segment of 

 the carpel, of which the terminal lobe, bearing the nucellus (when present) on its 

 upper surface, represents the inner, while the two lateral lobes represent the outer 

 integument; this is the extreme proliferated form. Between this and the normal 

 ovule every intermediate trandtional form has been observed, the e.xtent of prolifera- 

 tion depending on the stage of development of ovule at which the tendency thereto 

 sets in. Cases where proliferated outer integument appears as a simple lamina 

 bearing normal cup-shaped inner integument containing nucellus on its lower 

 surface ; this structure arises morphologically by fusion of the inner margins of 

 the two lateral lobes of the leaflet in the extreme proliferated form across the face 

 of the latter, the terminal lobe at the same time becoming inroUed. The whole 

 structure and mutual relationship of the parts is well shown by means of certain 

 abnormal forms of foliage-leaf in Stjringa. Hence the ovular integuments are the 

 morphological homologues of a three-lobed segment of the carpel. Id the normal 

 ovule the upper surface of the inner integument is directedinwards to the nucellus, 

 this latter being morphologically an emergence from that surface, while the upper 

 surface of the outer integument is directed outwards and away from the inner 

 integument. This applies to all cases : Brongniart, Cramer, Warming, (5elakoTsky, 



Gnetacea-. 



Gnetum has normally three envelopes surrounding the nucellus. Theories as 

 to their nature : — 



Some regard outer envelope as an ovary, others as a perianth, others again 

 as a third integument. The view maintained here is that it is a perianth, as two 

 integuments occur uniformly throughout Gymnosperms. 



Ephedra and Welwitschia each possess two integuments. Theory as to the 

 nature of outer integument in the former : perianth. 



Conifera, 

 Views as to nature of the sporangial appurtenances :- - 



Baillon, Parlatore, Sperk, and others regarded the single envelope as the ovary ; 

 almost all other botanists agree as to its integumental nature. Seminiferous 



