The Nardoo Plant 141 



PHYSIOLOGICAL OBSERVATIONS. 



Already in the winter, 1834-1835, the surprising observa- 

 tion was made by Professor Alexander Braun, how the 

 sporangia utricles of the Marsilea fruits, are protruded from 

 their receptacles by the expansion of a gelatinous placenta. 

 The latter became visible in the attempt of soaking the 

 fruit for more careful examination, and for the purpose of 

 effecting eventually its germination ; this took place in so 

 remarkable a manner, that it may not appear superfluous to 

 refer once more to the process, especially since only the 

 illustrations furnished by Alexander Braun, after his first com- 

 munication on the subject in " Der Regensburger Botanischen 

 Zeitung," 1839, p. 298, are hitherto published, the details of 

 the observations on Marsilea pubescens being solely illus- 

 trated in the "Exploration Scientifique d'Algerie, Botanique," 

 pi. 38, fig. 21-32, and remained unexplained by description. 

 After longer maceration of the fruit, Alexander Braun 

 observed that the valves of this and allied species were 

 seceding, a long, tender, gelatinous, vermicular body pro- 

 truded, from which on both sides opposite to each other the 

 sporangia utricles or sori expanded. A short explanation of 

 this process, from drawings of Alexander Braun, is given by 

 Professor Schnitzlein, in his " Iconographia Familiarum 

 Regni Yegetabilis," fasc. 2, f. 4, 7, 8, additions to the illus- 

 trations being furnished by Bischoff and Schnitzlein. 



Similar observations were made by Esprit Fabre (" Annales 

 des Sciences Naturelles, 1837, vii. 221 ; 1838, ix. 115, t. B.), 

 and by Mettenius ("Beitraege zur Kenntniss der Rhizo- 

 carpeen," 1846), who fully explained the development and 

 structure of the fruit of this and the allied genera. 



One of the fruits (transmitted by Dr. Schomburgk) in 

 order to facilitate the ingress of water was slightly split at 

 the ventral suture and was then boiled for about a quarter 

 of an hour in water, when the unusually long (placental) 

 cord, consisting of hyaline, transparent, elastic, cellular 

 tissue, was developed. This cord reached, gradually 

 extending after several hours, a length of 110 — 120 mm., and 

 a thickness of 4 mm. It bore on both sides, almost placed 

 by pairs, seventeen sporangia-utricles, likewise swollen. The 

 utricles of elongated form were fixed by stalk-like attenua- 

 tions to the cord and placed near each other at its inner side. 

 Each of these showed, as the (placental) cord itself on the 



