40 



CELLULAR TISSUE. 



2. The Initial cell is the direct Mother-cell of the stoma. Soon after it is marked off, 

 along each of its sides a narrow piece of the neighbouring epidermal cells is cut off by 

 walls running nearly parallel to each of the sides: and this takes place — 



a. Once in each of the contiguous cells: of these there are four, two bordering on the 

 ends, and one on each of the flanks of the stoma : there are therefore four subsidiary 

 cells corresponding in arrangement to these: Tradescantia^ species of Commelyna 

 (Fig. 13), Pothos crassinervia (usually), Pholidophyllum (see Fig. 12), Heliconia farinosa^, 

 Araucaria imbricata^; or 4, 5, and more: Ficus elastica (4-5), Coniferae*, Cycas, etc.; 

 also Strelitzia ovata (Fig. 28 A). 



i. Once in each cell bordering the flanks, so that the stoma is enclosed on either side 

 by a subsidiary cell similar to the guard-cells. This is the case in Graminese (probably 



Fig. 13. — Commelyna ccelestis ; leaf, development of the stoniata and subsidiary cells, surface view ^1 \'ery young. 

 S older sta^e ; .f in both the initial- and at the same time mother-cell of the stoma ; C mature, 5 ^uard-cells. Fron» 

 Sachs' Textbook. 



alP) and the foliage parts of other grass-like plants (Carex, Cyperus, Scirpus, Juncus 

 lamprocarpus, effu.sus, Luzula maxima), Stanhopea, Aloe soccotrina, nigricans, Musa 

 sapientum^, Claytonia perfoliata, Proteaceae (Protea"), Grevillea robusta®, Lomatia 

 longifolia, etc. 



c. By repeated division of the subsidiary cells separated as in a and I/, there arises 

 in many cases a double zone or a pair of subsidiary cells on each side. The former is 

 the case in Dioon ", the latter in Maranta bicolor, Commelyna communis, Pothos 

 argyraea, Hakea saligna, ceratophylla, and other Proteaceae (Strasburger J.c). 



3. The Initial cell is not the Mother-cell of the stoma, but divides further, once or 

 several times in succession, and the result of these divisions is a Mother-cell of the stoma, 

 and one or several subsidiary cells. The chief types of this are : — 



^ Strasburger, /. c. — Moldenhawer, Beitr. Tab. V. p. 94. — Meyen, Physiol. Tab. V ; Phytotomie, 

 Tab. III. pp. 4, 5. — Schleiden, Gnmdz. 3 Aufl. I. p. 277. 

 ^ Botan. Zeitg. 1871, Taf. I. 

 ^ Strasburger. /.c. — Hildebrand, Botan. Zeitg. 1S60, Taf. II. 



* Pfitzer, in Pringsheim's Jahrb. VII. p. 533, &c. 



* Strasburger, /. c. '^ Mohl, Spaltoffn. d. Proteaccen, Ic. ' Kraus, /.c. p. 335. 



