198 Linnaan Society. 



"It is curious," Mr. Griffith observes, " that this prolongation 

 [of the embryo-sac] has only been observed in association with a 

 particular form of the free central placenta. So far as I know," he 

 adds, " it is the onh' instance of an embryo- sac prolonged posteriorly, 

 it may be said, from two points of its surface." And further : " In 

 all the really analogous instances in which the albumen is exterior 

 to the ovulum, it is ahcays exterior, that part of the embryo-sac in 

 which it is developed being protruded long before any albuminous 

 tissue has been developed*." 



In conclusion, Mr. Griffith refers to the observations of Mr. Brown 

 on the ovula of Avicennia in the ' Prodromus Florae Novae HoUandisc,' 

 and in Dr. Wallich's ' Plantse Asiaticse Rariores,' and states that 

 the most important difference between this last account and that 

 which he has given is, that he finds the embryo 07ily to be erect. 

 " The embryo, in its earlier stages of development, undergoes a degree 

 of change of direction, but only sufficient to enable it to pass up out- 

 side the ovulum in the same direction it would have maintained had 

 it been ordinarilj^ developed." 



The paper was illustrated by a series of coloured drawings. 



December 3. — E. Forster, Esq., V.P., in the Chair. 



Read, some " Remarks on Vegetable Physiology." By Mr. James 

 Main, A.L.S. 



Mr. Main's object in the present paper appears to be the reproduc- 

 tion before the Society of the leading ideas on vegetable growth con- 

 tained in his ' Illustrations of Vegetable Physiology,' published in 

 1833, and to state his objections to some received theories on that 

 important subject. He denies the descent of the sap, and asks, " Who 

 has met with sapless branches in winter, or surcharged roots at the 

 same season?" He states that "the spring movement of the sap 



* In a IMemoir by M. Planchon, published at Montpellier, 1844, " Sur les 

 developpements et les caracteres des vrais et des faux arilles, suivi de con- 

 siderations sur les ovules de quelques Veroniques et de V Avicennia," it is 

 shown that in two species of Veronica (F. hedercefoUa and J\ Cymhalaria) 

 (and consequently in plants with the ordinary form of placenta) the nucleary 

 ovula are furnished with embryo-sacs, acquiring during the progress of their 

 growth two tubular ])rolongations, one from near each extremity, the upper 

 of which passes into the placenta, and there becomes digitately divided. In 

 these plants also the albuminigerous portion of the embryo-sac becomes, 

 during the progress of its development, external to the nucleus. In other 

 species of the same genus ( Ver. agresfis and V. arvensis) the ovula are 

 equally reduced to a nucleary form ; but the embryo- sac is much less de- 

 veloped at its extremities, and a tegument derived from the nucleus con- 

 tinues to enclose it up to the complete maturity of the seed. Comparing 

 these observations on Veronica with the desci-iption given in ISIS by M. A. 

 de St. Hilaire of the development of the ovulum of Avicennia, M. Planchon 

 comes to the conclusion, that " II devient impossible de ne pas considerer, 

 avec Brown, comme I'ovide lui-meme le corps oblong pris [par M. A. de 

 St. Hilaire] pour un cordon ombilical, et de ne pas voir dans le tubercule 

 arrondi qui sort de lafente du corps oblong, un sac embryonnaire analogue a 

 celui de la Veronique, et destine, comme ce dernier, a accomplir, hors du 

 nucelle, toutes ses evolutions." — Secr. 



