ANONACE^. 



257 



TJvaria} It is especially in Asimina triloha, a species of this last <^enus, 

 that we have been able to study the tissue of the stem and brandies 

 in the recent state, and this tissue we shall describe, remarking that, 

 generally speaking, it is that of the other genera we have examined. 

 The pith consists of two kinds of cells ; first, we have those of the 

 common parenchyma of Dicotyledons, all nearly similar, irregularly 

 polyhedral, the cell walls riddled with holes -^ secondly, we have 

 stony or sclerous cells, analogous to those of the pith of MafjuoUpoi, 

 forming incomplete transverse diaphragms here and there. Their 

 walls are very thick, traversed by numerous canals slightly dilated at 

 each end ; they refract light strongly, and are white or yellowisli in 

 colour/ The wood, rather light and soft," consists of narrow fibres 

 with very minute perforations and vessels of every kind. Certain 

 cylindrical thin-walled vessels, much larger than the rest, are 

 remarkable for tlieir very numerous perforations, placed close together 

 so as to form many rows, covering the whole surface of the vessel, 

 and almost touching by their areola?.* These are circular or elliptical 



' We should point out one exception, a Melo- 

 doi-um which Griffith (Xoinl., iv. 707, t. 650) 

 has described under the name of Ct/athosfemma. 

 In this plant, says the author, " the wood is 

 remarkable, the pith very small. The ligneous 

 system white, subcruciately -4-lobed, with con- 

 cave sinuses, and a secondary brown zone surround- 

 ing this, filling up the, concave sinuses, but very 

 thin opposite the angles. The vessels of the 

 white lobes are large, and frequently the me- 

 dullary rays are pronounced, complete, and white 

 in both systems, very large towards the circum- 

 ference, and generally containing one or two linear 

 bundles of white wood. These rays are distinct, 

 continuous from bark to pith ; the spaces be- 

 tween them {i.e., the wood) consist of fine dense 

 fibres, with a nearly simple zone of (scalariform) 

 vessels. The brown part consists of transverse 

 subundulate lines of woody fibre, and transverse 

 oblong spaces tilled with brown matter. These 

 brown spaces are divided by septa ; and pro- 

 bably the chief dift'erence between the brown 

 wood and the white is that in the brown the 

 vessels predominate so much as to subdivide or 

 break up the continuity of the fibrous part." 

 [In transcribing this passage from the original, I 

 have been compelled to make some alteration, 

 especially in the punctuation, in order to make 

 it intelligible.— Tkaxs.] 



Geiffith has described in the same work 

 three other genera of Anonaeece under the 

 names of PeUicaft/x, Fissistiffma (706), and 

 Nephrosligma (7l7) ; but from his very imperfect 



VOL. 1. 



description of these genera it is almost impos- 

 sible to discover if they would be included in any 

 of those we have studied above. Perhaps 

 PtUicah/x should be referred to Uvaria, and 

 Fiss}.^(u/ma to Mtlodorum. 



" Their contents are very variable. Here, as 

 in so many other plants, they are at certain 

 seasons gorged with starch-granules. We also 

 find crystals, either globular and studded with 

 little pyramidal points, or distinctly and regularly- 

 octahedral. 



^ Their contents are often yellow, oily-looking. 

 We have seen these thick-walled cells forming 

 diaphragms in the young branches of all the 

 AnoiHicece cultivated in our conservatories, ^«o»o 

 mto-icata and Cherimolia, Artalotrys uncata and 

 intermedia, and especially Xi/lopia athiopica, 

 where they presented very numerous distinct per- 

 forations with everted orifices. 



* De ilAKTirs has given the specific gravity 

 of the wood of several Brazilian Anouaceee (Fl. 

 Bra.s., Anonac, 61). He gives the following 

 figures: — Findaiha pveiafii ■^■j.mt Paul {Giiatte- 

 riajlava /), -839 (wood dense, yellowish, flexible) ; 

 Araticu do Mato {Eullinia syhatica) -530 (paler 

 and softer); Pindaiha branca.of Saint Paul (Xi/lo- 

 pia sericeaoT frutescens), '626 (colour browner); 

 Anona crassijiura, •571 (wood spongy, whitish). 



* We have met with these vessels in all the 

 species enumerated above, in many of which the 

 wall looks exactly like a sieve very regulaily per- 

 forated, and with the areolse touching by their 

 circumferences. 



