388 SYDNEY H. VINES. 



tigations on the salivary prlands (' Bericht der Sachs. Ges. 

 der Wiss. ; Math. Phys. CI.,' 1875, and 'Centralblatt/ 1875). 



It may be also mentioned that between the individual 

 muscular bundles of the pharynx there may be seen fine 

 intermuscular lymph-spaces lined by endothelial membranes, 

 an arrangement analogous to the interfascicular lymph-system 

 in connective tissue.^ 



I have to thank Dr. Klein, under whose direction these 

 investigations were made, for his advice and assistance. 



Some Recent Views as to the Composition of the Fibro- 

 VASCULAR Bundles o/ Plants. J5y Sydney H. Vines, 

 B.A., B.Sc, Fellow of Christ's College, Cambridge. 

 (With Plate XXVII.) 



In the consideration of this subject the first important 

 point is to distinguish Avith precision between the elements 

 which make up the fibro-vascular bundles and those which 

 belong to the ground tissue in which the bundles are arranged. 

 In those plants in which completely developed fibro-vascular 

 bundles first occur the limit between the fibro-vascular and 

 the ground tissues is clearly defined by means of one or more 

 layers of cells which form a sheath for the bundle (Kriten- 

 chyma or Koleochyma^) . In a fern, for instance, such as Pteris 

 aquilina (Fig.l, page 389), we find each fibro-vascular bundle 

 invested by a sheath of two layers of cells, and very fre- 

 quently it may be observed that the cells of the ground tissue 

 which are adjacent to these sheathing cells are of a brown 

 colour, have thickened walls and an elongated form. To a 

 mass of these thick-Avalled cells the name Sclerenchyma has 

 been given. 



It is evident that of the two layers of sheathing cells the 

 outer (a) forms the limit of the fibro-vascular bundle, and it 

 is rendered conspicuous by the absence of starch from its 



^ The arrangement of lymph-spaces in bundles of striped muscle-fibres in 

 the tongue, pharynx, and other organs, is precisely the same as that described 

 by Axel Key and Retzius in nerve-buudles, viz. Ijmph-spaces of the peri- 

 midium are in continuity with spaces lying between smaller groups of muscle- 

 fibres and penetrating even between individual fibres. The spaces are lined 

 by connective-tissue cell-plates. 



^ Russow, 'Vergleichende Untersuchungen, Mem. de I'Acad. Imp. de St. 

 Petersbourg,' t. xix. No. 1, p. 168, 1872. Also, idem, ' Betrachtungen 

 Tiber Leitbiindel u. Grundgewebe,' Dorpat, 1875, p. 71. 



