Rosaceæ. 39 



were already present. The simultaneous decrease of the 

 amount of the fat may indicate that some of this material 

 has heen used in the starch-formation, though naturally 

 nothing can be stated with certainty on this basis. Besides, 

 there are other materials than fat in herbaceous plants which, 

 like the latter, decrease in quantity during spring. 1 



The vascular bundles in the floral shoot vary greatly in 

 number (7 — 17) and are surrounded by a sheath of several- 

 layered stereom which is well-developed especially opposite 

 the vascular bundles; the outer part of the woody portion 

 of these bundles is connected with the bast-sheath, so that 

 the groups of sieve-tissue are surrounded by stereom. The 

 cortex is similar to that in Pot. pulchella. The outer wall 

 of the epidermis is about 5 « in thickness. The inner portion 

 of the pith breaks down. An endodermis is not present. 



The leaf of Pot. emarginata is most nearly mesophilous: the 

 thickness is about 170/*. Along the margin and along the bundles 

 of the leaf a fair number of long hairs occur; upon the surface 

 of the blades these hairs are fewer, but short-stalked glands 

 are rather numerous especially upon the lower surface (Fig. 

 15, A B), a fact which has also been observed by Abromeit 

 (I.e.). The outer walls of both upper and lower epidermis 

 are about 2/i in thickness; the inner walls of the upper epi- 

 dermis are not mucilaginous. As regards the radial walls of 

 the upper and lower epidermis the reader is referred to 

 figure 15, C and D. Stomata occur on both surfaces, but 

 they are more numerous upon the lower surface where they 

 may project slightly; upon the upper side they are on a level 

 with the surface. The coarse, somewhat barrel-shaped pali- 

 sade-cells occur in 2 — 3 layers. The proportion between the 

 leaf-thickness and the thickness of the palisade parenchyma 

 is found varying from | to -j- 



1 Ernst Michel, Zur Kenntniss der Jahresperiode unserer Stauden. 

 Inaug. Dissertât. Göttingen, 1909. 



