45° 



PRIMA RV ARRANGEMENT OF TISSUES. 



Where the pith is permanent, e. g. in the stems of spec.es of Ferula and the rh.zome of 

 Imperatoria Ostruthium \ the passages may be scattered through the whole pith. In the 

 numerous species with internodes which become hollow they are hm.ted to the persistent 

 periphery of the pith (Anthriscus vulgaris, Myrrhus, Carum Carv, Heracleum sp ) If 

 they are originally formed in the middle, and this is a pomt which is not decided, they 

 disappearwiththecellsofthepithsurroundingthem. In some cases however, the passages 

 persist in the middle of stems which become hollow, either surrounded by some layers of 

 pith-cells, and standing freely and singly in the hollow (Smyrnium Olusatrum), or em- 

 bedded in permanent lamells of pith, which extend from the periphery into the hollow 

 (Heracleum Sphondylium). , . ■ . i • 



The passages described run through the internodes as a rule with a straight, longi- 

 tudinal course, and few branches or anastomoses. There are, however, numerous branches 



at and near to the nodes, by which all anastomose one 

 with another, and are extended into the leaves and 

 axillary shoots. Blind endings have not been ob- 

 served. Also the sacs described in the old rhizome 

 of Imperatoria are only huge dilatations of the passages. 

 The passages have a similar distribution in the 

 petiole to that in the stem. Anastomoses, even of 

 reticulate form, occur at the points of insertion of the 

 segments of divided or compound leaves. The branches 

 finally enter the lamina. Here, according to Trecul's 

 observations «n Angelica silvestris, Opoponax, Impe- 

 ratoria, Smyrnium, Ferula tingitana, Lagoecia, &c., and 

 also in Eryngiura, they accompany the vascular bundles, 

 in such a way that they traverse the nerve both on the 

 upper and on the under side, in the latter position they 

 are on the average larger and more numerous ; there is 

 one in each of the smaller nerves, in the larger there are 

 often several ; further they are connected and in open 

 communication by means of their ultimate branches so 

 as to form a network similar to that of the .bundles. 



The sap-passages of the jiraliacex contain resin in 

 most cases investigated ; according to Tricul they 

 contain gum in Aralia chinensis, spinosa, Panax Lessonii, 

 P. crassifolium, &c. According to Trecul's investigations of numerous species of die 

 genera Hedera, Paratropia, Cussonia, and the plants already named, they are as generally 

 distributed in this family as in the UmbeUiferse, and the general plan of their arrange- 

 ment and course in root, stem, and leaves, as well as ''Bieir various modifications 

 according to single species, correspond so closely to those in the Umbelliferae, that 

 they need not be thoroughly entered into here, but reference may be made for many 

 details to Trecul" and N.,Muller {I.e.). In the roots of Hedera Helix and Aralia 

 Sieboldtii van Tieghem found the number and arrangement of the primary groups 

 near the vascular plates to be not always so very regular as in the Umbelliferae, and 

 those in the phloem to be either in contact with the pericambium, or completely 

 enclosed in the phloem. The numerous anastomoses between the radially undulated 

 passages of l^e primary (and also secondary) cortex of the branch of Paratropia 

 macrophylla observed by TrScul may here also be mentioned, and the statement of 

 the same author, that in the lamina of Panax Lessonii and crassifolium the passages 

 seem to occur in the mid-rib only, and apparently do not follow the lateral branches 

 of the vascular bundles. 



Fig. 193. — Transverse section through an 

 nternode of a young plant of Foeniculum offi- 

 cinale {40); pith surrounded by the partly num- 

 bered vascular ring. Between the bundles the 

 cambium zone connecting them is indicated ; 

 the small circle outside the stronger bundles is 

 the transverse section of an oil passage ; in each 

 of the blunt angles of the stem the transverse 

 section of a fibrous bundle is indicated in form 

 of a segment of a circle. Compare p. 241, 



' Compare Berg, Atlas z. Phaim. Waarenkunde, Taf. 22. — Wigand, Pharmacognosie. 



' Des Vaisseau-x propres dans les Araliacees; Comptes Rendus, torn. LXI. p. 1163 (1835). 



