The President's Address. By Dukinfield H. Scott. 141 



this is the important point — " that they served for the passage of 

 mobile bodies analogous to antherozoids " (Eenault, 1887, p. 156). 



If the second hypothesis should be confirmed, " it would 

 correspond," he says, " to an interesting phase in the evolution of 

 plants which is absolutely wanting in the recent vegetable 

 kingdom." At the close of the paper he adds : " We do not 

 regard as impossible the existence in the past of pollen-grains, 

 which, instead of effecting fertilisation by means of a tube, dis- 

 charged into the pollen-chamber of the appropriate seeds anthero- 

 zoids capable of performing this function " (p. 158). 



Thus the study of the phenomena presented by Palseozoic 

 fructifications led Eenault to anticipate, by some ten years, the 

 great discovery made at Tokyo by Ikeno and Hirase, that in the 

 lower seed-plants the cryptogamic or animal mode of fertilisation 

 by motile male cells still persists. The hypothesis was not one 

 thrown out at hazard, but was deliberately entertained, as shown 

 by Eenault repeating it on other occasions still previous to the 

 Japanese discovery (e.g. Eenault, 1896, p. 276). The case affords 

 a striking example, both of the acumen of Eenault himself, and of 

 the value of palseobotanical evidence in its bearing even on the 

 more minute points of morphology. 



M. Eoche informs us that the scientific work left uncompleted 

 at the time of Eenault's death, relates chiefly to the fecundation 

 and reproduction of permocarboniferous plants. 



6. The Question of Secondary Wood. 



In Dicotyledons and Gymnosperms, as we all know, both wood 

 and bast possess the power of indefinite growth in thickness, by 

 means of a layer of permanently, or periodically, active tissue, the 

 cambium, which constantly adds new elements to both. On 

 account of this method of increasing the mass of their vascular 

 tissues, the name of Exogens was formerly applied collectively to 

 the two classes in question. The capacity for exogenous growth, 

 or as we now call it, the production of secondary wood and bast, is 

 at the present time, no doubt, a great characteristic of the higher 

 plants, though still by no means limited to them. Among the 

 Vascular Cryptogams now living, instances of secondary growth 

 in thickness are rare (e.g. Botrychium, Isoetes, and in a smaller 

 degree Psilotum), and were not clearly recognised at the time when 

 the structure of fossil plants first became the subject of scientific 

 study. Hence, when the great Brongniart found that in Sigillaria 

 and Calamodendron exogenous growth certainly took place, he was 

 led to give up the view of their Cryptogamic affinities, and to class 

 them with Gymnospermous Dicotyledons. The secondary wood, 

 in fact, was looked on as a decisive Phanerogamic character, and 



