298 Count Gaston de Saporta on the Part played 



or even uniquej in most cases^ but they belong to very different 

 organs. The fruit of the Betula occurs in a different stratum 

 from that which contains the leaf. The fruit of the Populus has 

 been found isolated from its leaf, and the latter separate from a 

 ciliated bract, probably forming part of the same species. The 

 involucra of Ostrya are not yet accompanied by their leaves ; 

 there exist a leaf of Ulmus, but hitherto no trace of its fi-uit, 

 and leaves of Acer without any fruit. We must therefore notice 

 a very great irregularity in the mode of transmission of the 

 organs; and all that we can conclude from the state in which 

 they have come down to us is, that no obstacle difficult to get 

 over has stood in the way of their reaching the waters of the 

 lake, that they did not get there from any great distance, and 

 that small and delicate organs, especially those of fructification, 

 have been preserved pretty frequently in a state of perfect inte- 

 grity; whilst, on the other hand, winged fruits, easily carried 

 by the wind, are sometimes wanting, in cases where the leaves 

 have, on the contrary, passed into the fossil state. 



What are we to conclude from these various observations, if 

 not that the hypothesis first put forward as the most natural 

 in appearance is at least contestable from the side of the facts ? 

 that these facts do not tend to confirm it, and would, on the 

 contrary, rather lead one to think that the plants with a Euro- 

 pean physiognomy and deciduous leaves, although evidently ex- 

 cluded from the vegetable masses of the epoch, and forming 

 arborescent groups of considerable size neither on the immediate 

 margin of the waters nor in the vicinity of the ancient lake, do 

 not appear nevertheless to have occupied a very distant station ? 

 and lastly, that their organs have reached the sediments in 

 course of formation with complete irregularity, and without the 

 aid of the wind having contributed to augment the proportion 

 of such organs as the winged fruits, by assisting them to get 

 over greater distances ? It remains for us, therefore, to seek 

 another series of hypotheses more in accordance with the facts. 



Perhaps the plants in question, not possessing originally the 

 appearance, size, and habits which they subsequently acquired, 

 isolated in the midst of the robust plants of the period, only 

 occupied a secondary place among them, which would explain at 

 once their rarity as individuals and the limited proportional 

 quantity of their organs, of which only a very small number could 

 reach us. 



On this hypothesis we should have to establish three points 

 with regard to the plants under consideration: — (1) a sensible 

 difference in their habitual station ; (2) a peculiar mode of group- 

 ing, a natural consequence of the preceding, producing a greater 

 rarity oi individuals ; (3) lastly, a comparatively small stature, — 



