423 



stage of a horizontal one which I observed had from one to a 

 few vessels in the eight masses of wood, and an incomplete 

 ring of sclerenchyma, no doubt outside and also including the 

 endodermis, but the latter was not distinct. A later stage showed 

 the ring of sclerenchyma 1 — 3 layers thick, in a complete 

 condition ; still later, the thin-walled primary cortex, 5 — 6 layers 

 thick, was found to be collapsed, and in the full-grown stage 

 it had been thrown off together with the sclerenchyma-layer. 

 The epidermis is one-layered and thin-walled. The secondary 

 cortex has on the outside some layers of dead, suberized cells, 

 and within these a somewhat collenchymatously thickened part; 

 the innermost part is thin-walled and the cells are arranged 

 radially. 



The wood-masses are either fused together or are separated 

 by narrow medullary rays from which cambium is absent; 

 otherwise the latter is complete. The cells of the pith are 

 thin-walled and more or less collapsed in the older rhizomes. 

 The structure of the vertical part of the rhizome was similar 

 to that of the horizontal part, only it was thicker, the course 

 of the bundles was irregular and thin-walled parenchyma was 

 more abundant among the secondary vessels. 



The peduncle is short and thick and pentagonal. The 

 epidermis is fairly thick and contains chlorophyll; the cuticle 

 is smooth, and the stomata are on a level with the surface. 

 The cortex is 5 — 6 layered and consists of fairly closely placed 

 cylindrical cells ; intercellular spaces are absent between the 

 subepidermal layer and the epidermis. In the outermost layers 

 in the angles of the peduncle, only very little or no collen- 

 chyma occurs; such a tissue is found in other species of 

 Thalictrum. Outside the 7 — 10 bundles there is a ring of 

 bast which, opposite to the bundles, is as much as 7 layers 

 thick while in the interfascicular part about three layers are 

 found: the sieve-tissue occurs close to the bast-layer; in the 

 adult peduncle no endodermis was to be seen; the cambium is 



