TANNIN-SACS. 



153 



4. Tannin-Sacs. 



Sect. 35. The secretion of Tannin in large quantity in the sacs of Sambucus 

 suggests the idea of placing other sacs or cells with large quantities of tannin in the 

 category of secretory sacs. It is true the presence of this body in large quantity is 

 not decisive, since it occurs also in other places, as in the epidermal cells, and in 

 many plants, especially ligneous ones, particularly in the assimilating, starch-forming 

 parenchyma, and since, as far as we know at present, it is at least undecided whether 

 it appears as a secondary product of the constructive metastasis, as is the case with 

 calcium oxalate, or as an integrating transitional member of it. Further, with the 

 exception of the tannin, too little is known of the structure, and especially of the 

 character of the contents of the organs, which are possibly to be distinguished as 

 tannin-sacs, for us to be able to decide whether, and when, they are to be regarded 

 as secretory sacs, or only as parenchymatous cells rich in tannin. But there are a 

 number of organs which, as far as may be concluded from information at hand, have 

 apparently lost the properties of cells, and are the points of secretion of mixed 

 substances requiring further investigation, amongst which tannin takes permanently 

 the most prominent place under the reagents at present in use : these organs 

 correspond further in many cases, in their early appearance and position with regard 

 to the vascular bundles, to the secretory sacs of Sambucus, the Cynarese, Aceracese, 

 &c., also to many intercellular, secretory reservoirs, and may therefore be substitutes 

 for these. Awaiting more exact investigation, and excluding such as contain starch 

 as well as tannin, we may here introduce these organs as Tannin-sacs. 



They occur as elongated sacs, especially near to the vascular bundles, in the 

 parenchyma of the stem and petiole of many Ferns (Marsilia, Polypodiacese, 

 Cyatheaceae, Marattiacese ^, &c.). 



Among the families of Monocotyledons, the Araceae and Musacese should be 

 mentioned as having those rows of sacs, to be described in Chap. VI, which accom- 

 pany the vascular bundles. Also the laticiferous tubes of these plants, consisting of 

 coalesced sacs, would be better placed here than with the rest of the laticiferous tubes 

 in Chap. VI. 



Of the Dicotyledons certain Leguminosae may without doubt be mentioned 

 here. In Phaseolus multiflorus Sachs ^ found in the phloem of the primary vascular 

 bundles of the stem and leaves (but not continued into the root) longitudinal rows of 

 prismatic tannin-sacs arranged singly or in small groups. They form in transverse 

 section a broken series of curves. A similar arrangement appears in a similar place 

 in the transverse section of the branches of Robinia pseudacacia ^ The sacs are 

 here 6-8 times as long as broad, cylindrical, with rounded ends, and only attached 

 to one another by the flattened middle of the terminal surfaces. A group of rather 

 wider series of sacs, with longer members filled with tannin, lies in these trees in 



' Von Mohl, Baumfarne, Verm. Schriften, p. 1 1 3.— Martius, Icones pi. Crypt. Brasil. Taf.XXXI 

 and XXXIII. Compare also Karsten, Vegetationsorgane d. Palmen, /. c. p. 205.— Trecul, Comptes 

 Rendus, Mai, 1871, and Ann. Sci. Nat. 5 ser. torn. XII. p. 373.— Russow, Vergl. Untersuchungen. 



^ Unters. iiber d. Keimung d. Schminkbohne, Wien (Acad.), 1859. 



' Hartig, Foistliche Cultnrpfl. p. 546. 



