BAST. 197 
In the monocotyledons the bundles of bast-cells surround the 
vascular bundles, either in a sickle-like manner (as in the stem 
of the maize, Fig. 133), or lie embedded in the remaining 
tissue, sometimes in the inner portion and sometimes in the 
outer, as isolated bands, rings or bundles, according to their 
function, or they surround the outer side as a connected coat? 
Fie. 112.--Transverse section through an involute leaf of the Alfa grass or Esparto 
(Macrochloa tenacissima). a, bast-cell coating of the outer (under) side; d@, assimilating 
tissue; c, prisms of the upper side; b, hairs (Tschirch). Compare Pharm. Zeit., 1882, 
No. 68, : 
principal work; furthermore, Th. v. Weinzierl, ‘* Beitrége zur Lehre 
von der Festigkeit und Elasticitaét vegetabilischer Gewebe.” Sitzungs- 
berichte der k. Akademie der Wissensch., Vienna, 1877, Vol. 76. F. 
Lucas, “ Beitriige zur Kenntniss der absoluten Festigkeit von Pflanzen- 
geweben.” Sitzungsberichte der Wiener Akademie, 1882, Vol. 85, and 
1883, Vol. 87. 
‘In some of these cases (especially in the prairie grasses), they serve 
in the mechanism which causes the involution of leaves (Tschirch, 
Pringsh. Jahrb., xii.). In the dehiscence of fruits, and the phenomena 
of torsion of many awns, mechanical cells are also concerned [Stein- 
brinck, Inaugural dissertation, 1873, and ‘‘ Berichte der Deutsch. Bot. 
