Gymnogens.] 



GNETACE.E. 



233 



on the stnictm-e of Gnetuni, he shows that m reahty the whole of the apparatus belongs 

 to the ovulum. In that ISIemoir (dated Aug. 4, 1835), which unfortunately did not reach 

 me till after the publication of the last edition of this work, there is the following 

 description of the development of the parts of this extraordinary structure. 



" At a period long before the exsertion of the anthers, the oaoiIcs, which He upon the 

 male flowers, are generally of an oblong fomi, and consist of a central cellular sohd 

 body, inclosed in two envelopes. The outermost of these is fibro-cellular and divided 

 longitudinally on the upper face, or that nearest the axis ; the fissure extending nearly 

 to the base of the o\'ule.* The inner or second envelope is cellular, and is divided 

 in'egularly towards its apex. 



" This envelope does not at this period entirely inclose the nucleus : the points of some 

 of the lacinite or di%asions project occasionally beyond the apex of the outer envelope. 



The nucleus is an oval or oblong cellular body, 

 rounded off at its apex, wliich is composed of 

 lax cellular tissue, 



" The next change consists in the commence- 

 ment of the obhteration of the longitudinal 

 fissm'e, existing along the posterior face of each 

 outer envelope, and of an extension of the 

 inner coat over the nucleus, the apex of which 

 becomes more or less depressed : the centre 

 of the depression, however, projecting in the 

 form of a cone of a very slight elevation. At 

 the time of flowering, or of the exsertion and 

 dehiscence of the anthers, the fissure originally 

 existing along the upper face of the outer coat 

 has disappeared ; with the exception of a small 

 4 portion at the apex of the o\aile, which 

 remains imclosed throughout. The o\Tiles are 

 at this period in some species obhque. The 

 inner envelope is generally entirely inclosed 

 within the outer ; the pomts of its laciniae reach, 

 however, to the openmg existing m the apex of 

 this latter, and occasionally, but by no means 

 imiversally, project beyond it to a short distance. 

 This coat has imdergone scarcely any change, and corresponds 

 in shape to the ca^ity of the outer envelope. The nucleus 

 is completely covered by both mteguments, and its apex, 

 which continues of the same form, is occasionally tinged with 

 brown. Within its substance, which is entu'ely cellular, and 

 towards its centre, there exists a small cavity, lined with a 

 membranous sac, attached apparently to the apex of the 

 ca\'ity, and containing a number of mmute grumous-looking 

 browTi masses arranged without any obA^ous regularity. 

 This sac I consider to be the amnios, with which it agrees in 

 its development and subsequent disappearance ; it exists at a 

 rather early period, and is developed withm a ca\dty formed 

 by some excavating process. 



«A short time after the fall of the male flowers an extra- 

 ordinary change will be found to have occurred, consisting 

 of the very rapid and apparently sudden development of a 

 new membrano-cellular envelope between the second coat 

 Fig. CLXIV. ^^^ ^j^g nucleus. This new formation, which I may term 



the additional coat, envelopes the nucleus pretty closely, and is contmued upwards 

 beyond the apex of the nucleus into a cylmdi-ical tubular process ; the mouth ot the 

 tube being lacmiate or fimbriated. At the period now refenred to, its apex barely 

 projects beyond the outer envelope. During its development no particular change has 

 taken place either in the original mtegiiments or nucleus. At a somewhat later period, 

 the ovules, except in the instance quoted in the note, hitherto concealed by the involu- 

 cre, will be found exposed, and the outer coat to have become of a green colour, t 



" * This division is perhaps similar to that which Brown states to take P^^^^^ in Dacrydium." 

 " t In one species, G Brunonianum, the o^niles are at an early period exposed, ovang to the obsolete 



ness of the annulate involucre." 



Fig. CLXIV.-Analysis of Gnetum, from sketches hy Mr. Griffith ; 1. a ring of ^ and ? flowers ; 



2. a ^ ; 3. a perpendicular section of a ^ , showing the 3 membranes overlying the nucleus ; 4. an em- 



bno extracted, with its long funicle. 



