48 



the wild cherry, 1 privet, elder, ash, and willow, the lenticels arise under 

 one stoma, and in the black walnut and poplar under several, by the 

 separation of the parenchyma cells underneath and surrounding the 

 breathing pores. In other plants— for example, barberry, broom-corn, 

 currants, and other species of Ribes— the lenticels originate in the cork 

 cambium (phellogen). In the potato the rind is composed of tabular 

 cork cells (Fig. 1 £), and under this, as well as below the stomata 2 the 

 first beginnings Of the lenticel formation occur in the form of irregular 

 cells containing but little protoplasm. (Fig. 1 a). The formation of 

 these cells is continually penetrating farther in, while the cells first 

 formed absorb water, swell up, and burst the cork rind, thus forming 

 the scab-producing lenticel, from which the loose cells within (Fig. 1/) 

 emerge in a whitish, moist, flour like mass. These cells soon degener- 

 ate, and the process of degeneration extends inward, so that the com- 

 pact, united lenticel cells (Fig. 1 v) must always be looked for deeper 

 and deeper in the flesh, and the starch (Fig. 1 st) disappears propor- 

 tionally from the surrounding tissue. 



We have, therefore, two processes to consider in the formation of 

 scab; the first is the growth of lenticel cells, which proceeds until the 

 discharge of the flour-like cell mass; and the second consists of thede- 



1 E. Stalil, Eutwicklungsgeschi elite imd Anatomie der Lenticellen, Bot. Zeit., 

 is;:;, Nr. 36-39. 



2 Caspari in Sitzuugsbcrichtcder niederrneinischen Gesellsckaft iurNatur-undHeil- 

 kunde, v. 8, Jan., 1857, cited in Bot. Zeit., 1^57, p. 116. 



