2 CELLULAR TISSUE. 



c. Initial cell divided by an annular wall into jNIother-cell and annular subsidiary cell: 

 Polypodiuni lingua (Rauter, /. c). 



According to what has been said, subsidiary cells of special form originate in all the 

 cases given under 2 and 3 : in those under i only when the U- or annular-form of the 

 first boundary wall necessitates special peculiarities of form. The mode of formation 

 may be always recognised in the known cases in the mature state, but with varying 

 sharpness, according as the subsequent growth of the cells in surface and height sharpens, 

 retains, or obliterates the original distinctions. 



Oscillations and transitions between the related types are by no means rare. For 

 details comp. Strasburger and Pfitzer /. c. As regards occasional malformations, we 

 must here again return to the twin stomata, /. e. those which appear in contiguous pairs, 

 and refer to Pfitzer's detailed statement \ according to which these may arise by means 

 of many different anomalies of division. 



Two normal exceptions must here be somewhat more carefully described. First that 

 of Aneimia, discovered by Link, later for a long time much discussed, and misunder- 

 stood, and finally explained by Rauter, who showed that the same was the case in 



Fig. 16. — Aneimia hirta ; leaf, epidennis. a, b mature ; a surface view, * section perpendicular to the surface, 

 median through the stoma (375). r, d very young {6co) ; c surface view with one fully-developed stoma, and five 

 mother-cells as yet undivided ; the protoplasm of these has contracted from the delicate membrane through the 

 process of preparation; h unicellular hair; (^perpendicular section through a mother-cell of a stoma with the sur- 

 rounding cells. 



Polypodiuni lingua. In these cases the stoma is surrounded by one annular Epidermal- 

 or subsidiary cell '^ 



The remarkable point in this phenomenon is nothing more than that the wall of the 

 mother-cell in normal cases has the form of a ring set at right angles to the surface, 



* Pringsheim's Jahrb. VII, p, 551. 



^ Link, Ausgewahlte anatom, Abbildungen, Heft III. Taf, IV. 8.— Oudemans, Bulletin du 

 Congres de Bot.inique, &c. a Amsterdam, 1865, p. 85.— Hildebrand, Botan. Zeitg. 1866, p. 245.^ 

 •Strasburger, in Pringsheim's Jahrb. V. /. c. ; also VII, p. 393, Anm,— Rauter, /. c. 



