198 BOTANICAL GAZETTE [septemeer 



gonia. They are formed 



underl}' 



epidennal 

 By repeate 



Vines 



stomata 



of the formation of air chambers according to Leitgeb- From that 

 time to the present Leitgeb's views have prevailed, being repeated 

 in all the textbooks as settled fact. As Campbell in the new edition 

 of Mosses and ferns nowhere definitely describes the origin of air 



,^ we quote and translate from Goebel's Organographie 



(p-296): 



It is characteristic of the Marchantiaceae and Ricciaceae that air chambers 

 are found in the nutritive tissues. These arise, as Leitgeb first showed, not at 



3 Sitzb. Kais. Akad. Wiss. Wien 81:40-54. pi. i. 18S0. 



4 Campbell casually uses this expression {op. cit., p. 39) regarding Riccia iricho- 

 car pa: "At first the cells of the young thallus are without intercellular spaces, but at 

 an early period the outer cells of the young segments separate and form the beginnings 

 of the characteristic air-spaces" [italics ours]. Inasmuch as Campbell follows Leit- 

 geb's account for other Ricciaceae, so far as he gives any description of the air-chamber 

 formation, these nhra^^et; cf»pm tr» "ha^ro >^^t^ o^^;^^«*-„ii,, „« *. 



t 



mural rows of cells lying between the air ca\dties, the lid of the cavity is carried 

 rapidly upwards. This epidermal cell, which closes the air cavity, forms itself 

 into a stomate. 



HoiMEiSTER also speaks of air cavities being formed in the '^stem" 

 by the lifting-up of a "single layer of cells," of \Yhich the central one 

 divides to form the ring that opens as a stoma. 



This conception is obviously that of schizogenous formation, but the 

 separation was ascribed to the upgrowth of the lateral walls of the 

 chamber as the base and roof widen. With the exception of the 

 detachment of a single epidermal cell, what Hofmeister describes 



w _ 



actually happens; but he observed only the later stages of develop- 

 ment and not the origin of the chambers. 



This alleged origin was accepted by Sachs and was described by 

 him in the Lehrhuch der Botanik of 1874, whence it found its way into 

 the English edition, issued in 1882. There the statement occurs J 



(under the topic Iniercellidar spaces ^ be it noted) : 



The epidermal cells become detached from those lying beneath over rhom- 

 boidal areas, which are marked off from one another by w^alls formed of cells which 

 are not detached. 



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