PHANEROGAMIA : FLOWERS. 399 



all (?) Monocotyledons. The simple integuments, the outer always 

 and the inner sometimes, in Thymelacea, Lauracece, Euphorbiacece, 

 and Cistacece, are composed of parenchyma, clothed on both surfaces 

 with epithelium. Vessels and vascular bundles are never met with 

 in nuclei or the integuments ; usually, however, a vascular bundle 

 traverses the funiculus and the raphe where they are present, but 

 always terminates in the chalaza, frequently in a clavate group, or 

 in a flat or concave expansion of spiral-fibrous cells. The funi- 

 culus is likewise clothed with epithelium, as an immediate continua- 

 tion of the epithelium of the seed-bud. 



The most important circumstance, however, is the change that 

 takes place in the structure of the nucleus. Originally, this con- 

 sists of a homogeneous, delicate, uniform parenchyma, but soon, and 

 simultaneously with the first appearance of the integuments, one in- 

 dividual cell is excessively distended, displaces gradually more and 

 more of the parenchyma around, which becomes dissolved and 

 absorbed, and forms a cavity in the interior of the nucleus, clothed 

 with a simple, structureless, membrane : this cell is the embryo-sac 

 (sacculus colliquamenti vel satius amnii of Malpighi ; the quintine of 

 Mirbel, the sac embryonnaire of Brongniart.) Its form is very 

 various, usually oval, often a slender filiform cell in the axis of 

 the nucleus, the part towards the point of which is considerably 

 swollen (as in Amygdalus.) Its contents are gum, sugar, or mu- 

 cilage ; very rarely it is gradually filled with cellular tissue before 

 impregnation, as in the Asclepiadacea. In extremely rare cases (so 

 far as is at present known, only in Viscum), two or three embryo- 

 sacs are formed simultaneously. 



The anatomical structure of the seed-bud is extremely simple, and I 

 know of nothing important to be added to the above statements. Link 

 says, " Where the funiculus enters the seed, a variously-shaped body 

 often exists, which originates from the thickened and expanded funi- 

 culus, but clothed with an epidermis, of which the funiculus is destitute." 

 Neither funiculus nor seed-buds or seeds, nor any part of them (with the 

 exception of Canna and Nelumbium), have an epidermis with stomates. 

 The funiculus is clothed by epithelium as well as the' seed-bud (or the 

 seed.) Link cites as an example, the caruncula in Euphorbia (which 

 certainly, as I have already said, does not refer here), but in this very 

 instance no epidermis, nay, even no epithelium, can be distinguished, 

 since it is wholly composed of delicate, transparent, and somewhat elon- 

 gated cells: on the other hand, the short thick funiculus has a most 

 distinct epithelium in this very instance of Euphorbia. 



The only essential anatomical point is the development of one cell of 

 the nucleus into the embryo-sac,* This, so far as I can judge at pre- 

 sent, exists in all Phanerogamia without exception ; I venture to assert, 

 ^at I have examined at least 500 plants of the most diiferent families 



* Link (Elem. Phil. Bot. ed. 2. vol. ii p. 283.) says, " Malpighi's sacculus colliqua- 

 menti, which Robert Brown meant, Mirbel not" Link has not read Mirbel properly : 

 he expressly says, " la quintine est la vesicule de famnios, Malpighi,'' &c. Link further 

 says, " This sac'is filled with cellular tissue." This is untrue of at least one-tenth of the 

 Phanerogam ia. 



