Section IV, 1888. [ 97 ] Trans. Roy. Soc. Canada. 



IX. — Oil the Ny inphœaceai. 

 By George Lawson, Ph.D., LL.D. 



(Read May 22, 1S88, with subsequent additions.) 



Part I. 



Structure of Victoria regia, Liiullcy. 



(Abstract.) 



An acoonut was giveu of the general conformation, and of the arrangement of tissue 

 systems in the organs, of plants belonging to the Natural Order Nymphœaceœ, or Water 

 Lilies, and of sisecial features in their organization and minute anatomy. The South 

 American "Water Lily, Victoria regia, had been, many years ago, fully described and illus- 

 trated, in respect to its general botanical characters and history, successively, by Dr. 

 Lindley, Sir William Jackson Hooker, Mr. Thomas Moore, and the author of the present 

 paper. As regards its minute structure, it was more carefully studied by M. Planchon, 

 whose researches were published in the Flore des Serres, Vol. VI, p. 249, etc., and by M. 

 A. Trécul, who illustrated the more important facts of its structure and development of 

 organs in the Annales des Sciences Naturelles, Botanique, ser. 4, 1, pp. 14.5-1'72. Some of 

 the facts well known a quarter of a century ago seem to be forgotten now. Lately, De 

 Bary, in the " Comparative Anatomy of Phanerogams and Ferns," and J. H. Blake, of 

 Cambridge, in Balfoiir's "Annals of Botany," August, 188t, questioned the explanations 

 given of the structure of the prickle in the Victoria, so far as regards the nature and 

 function of the ostiole or depression at its apex. The author of the present paper had 

 shown, as long ago as 1855, the true character of these prickles, and that the so-called 

 ostiole had no special function, as had been argued (and inferentially was not j)atholog- 

 ical, as now suggested by Blake), but that it was " a simple depression in the apex 

 of the prickle of no physiological importance," (Proceedings Bot. Soc. Edinburgh, 

 November, 1855.) In the same paper it was shown that the stomatodes, or perforations 

 of the leaf, were not mere holes caused by insects, as argued by Trécul, and now accepted 

 on his statement by Blake, but special structures of uniform size, formed by a surround- 

 ing margin of modified cells ; further, that they were comparable with the more com- 

 plete reduction of parenchymatous tissue seen in many submerged plants, and especially 

 in Ouvirandra fenestralis ; moreover, their probal)le special function, as a contrivance for 

 securing the drainage of water from the upper surface of the gigantic, tray-like leaf, 

 with upturned margin, was indicated. 



A series of large, coloured drawings, illustrating the microscopical structure of the 



Sec. IV, 1888. 13. 



