4° 



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 S 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), Coniferse', Cycas, etc.; 

 also Strelitzia ovata (Fig. 28 A). 



6. Once in each cell bordering the^nks, so that the stoma is enclosed on either side 

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



Fig. 13. — Commelyna ccelestis; leaf, development of the stomata and subsidiary cells, surface view ^ very young, 

 B older stn^e ; s in both the initial- and al the saine time mother-cell of the stoma ; C mature, .? guard-cells. From 

 Sachs' Textbook. 



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

 lamprocarpus, effusus, Luzula maxima), Stanhopea, Aloe soccotrina, nigricans, Musa 

 sapientum^, Glaytonia perfoliata, Proteaceae (Protea"),' Grevillea robusta^, Lomatia 

 longifolia, etc. 



c. By repeated division of the subsidiary cells separated as in a and b, 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, eeratophylla, and other Proteaceae (Strasburger Ac). 



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 stoina, 

 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, Grundz. 3 Aufl. I. p. 277. 

 " Botan, Zeitg.'i87i, Taf. I. 



' Strasburger, /. c— Hildebrand, Botan. Zeitg. i86o, Taf. II. 

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

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



