62 



Excerpta Botanica. 



XII. — Excerpta Botanica, or abridged Extracts translated 

 from the Foreign Journals, illustrative of, or connected with* 

 the Botany of Great Britain, By W. A. Leighton, Esq., 

 B.A., F.B.S.E., &c. 



No. 2. On the mode of Growth of the Ophioglosseag. By 

 Alex. Braun. (Ann. des Sc. Nat. n. s. xiii. p. 63.) 



The cellular body from which, in the genus Ophioglossum, 

 the leaves arise, is not a sheathing leaf, nor of the nature of a 

 stipule or a ligule ; but is, in reality, a cellular body envelop- 

 ing the centre of development, on the exterior of which centre 

 the leaves are arranged in a regular spiral order, and in which 

 situation they continue until their expansion, which, in Ophio- 

 glossum vulgatum, takes place in the fourth year. In this 

 body each leaf occupies its own particular cellule, which, en- 

 larging with the growth of the leaf, is in succession elevated 

 into a conical form and becomes finally ruptured like a sheath. 

 The spike in Ophioglossum is axillary, and is the solitary leaf 

 of a bud developed in the axil of the sterile leaf, to the stalk 

 of which that of the spike is agglutinated. In the genus 

 Botrychium, at least in the advanced state in which alone it 

 has been hitherto examined, this enveloping cellular body 

 does not exist, but the leaves ensheath each other. M. Braun 

 considers the cellular body in Ophioglossum as a thalloid for- 

 mation remaining during the entire life of the plant, and cor- 

 respondent to the cellular organ through which the primary 

 leaves of germinating ferns penetrate, and to which the name 

 of proembryo has been given. As in the Phanerogamae the 

 first commencement of a plant gives birth to a leaf developing 

 itself in the interior of a cellular organ (the sac embryonaire), 

 so it would appear that throughout the whole vegetable king- 

 dom the formation of a thallus precedes the formation of 

 leaves. 



PROCEEDINGS OF LEARNED SOCIETIES. 



GEOLOGICAL SOCIETY. 



December 4, 1839. — A paper was first read, entitled "A Descrip- 

 tion of the Soft Parts and of the shape of the Hind Fin of the Ichthyo- 

 saurus, as when recent," by Richard Owen, Esq., F.R.S., F.G.S. 



The osseous frame-work of the fin of the Ichthyosaurus, Mr. Owen 

 observes, having alone been the subject of direct examination, the 

 exact shape and the nature of the soft parts had been matters of 

 conjecture. A very striking deviation from the reptilian and mam- 

 malian types had, indeed, been recognised, and resemblance also to 



