THE CHLOROPHYLL-BODIES. . 49 



Irietal, their growth in length and breadth is generally proportional to that of the 

 11-wall and protoplasm in which they lie. But if the growth of the cell is very 

 considerable, the growing parietal chlorophyll-granules divide ; this takes place by bipar- 

 I tition,, in a direction at right angles to the longest diameter, into two secondary granules 

 i usually equal in size. • If it contained small starch-grains before the division, these 

 arrange themselves round the centres of the newly formed granules. These processes 

 are inferred from the increase of the number of granules on the one hand, and from 

 the frequent occurrence of constricted hour-glass- shaped forms on the other. After 

 this bipartition had been discovered by Nageli in Nitella, Bryopsis, Valoniay and in the 

 prothallia of Ferns, it was subsequently noticed in all the families of Cryptogams which 

 form chlorophyll ; among Phanerogams also it appears widely distributed ; it was dis- 

 covered by Sanio in Peperomia and Ficaria, subsequently by Kny in Ceratophyllum^ 

 Myriophyllum, Anacharis, Utricularia, Sambucus, Impatiens, &c. In cells of the prothal- 

 lium of Osmunda exposed to feeble light and containing but little chlorophyll, Kny 

 states that moniliform rows of chlorophyll-granules are produced by repeated bipartition, 

 which, like the chains of cells of Nostoc, continue to elongate by intercalary divisions ; 

 branching takes place also, in a manner similar to that which occurs in Nostoc, some 

 of the chlorophyll-granules increasing in size transversely, and producing branch-rows 

 by division. 



(c) With reference to the Internal Structure of the Chlorophyll-bodies, scarcely any- 

 thing more can be said than that their outer layer often appears denser, and that the 

 proportion of water increases towards the interior, the cohesion decreasing, as is apparent 

 from the formation of vacuoles. A differentiation into intersecting layers of different 

 density has only been once observed, by Rosanoff, in old chlorophyll-granules of Bryopsis 

 plumosa. 



Sect. 7. Crystalloids^. — A portion of the protoplasmic substance of a cell 

 sometimes assumes crystal-like forms ; bodies are produced which, bounded by plane 

 surfaces and sharp edges and angles, possess an illusory resemblance to true crystals, 

 even in their behaviour to polarised light ; but they are essentially distinguished from 

 crystals by the action of external influences, and at the same time present significant 

 resemblances to organised parts of cells. It is therefore legitimate to distinguish 

 them by the term Crystalloids'^ proposed by Nageli. They are usually colourless, 

 but sometimes act as vehicles of colouring matters (not green), which may be 

 removed from them. Their substance exhibits all the more essential reactions 

 of protoplasm, its power of coagulation and of taking up colouring matters, the 

 yellow reaction ^\\\h potash after treatment by nitric acid, as well as that with iodine. 

 The solubility of diflferent crystalloids is very different, as is generally the case with 

 proteids. They are capable of imbibing water, and swell up enormously under 

 the influence of certain solutions ; their outer layer possesses greater power of 

 resistance than the inner more watery mass. Those crystalloids which have been 



^ Hartig, Bot. Zeitg. 1856, p. 262. — Radlkofer, Ueber die Krystalle proteinartiger Korper 

 pflanzlichen und thierischen Ursprungs, Leipzig 1859, — Maschke, Bot. Zeitg. 1859, p. 409. — Cohn, 

 Ueber Proteinkrystalle in den Kartoffeln, in the thirty-seventh Jahresbericht der schlesischen Gesell- 

 schaft fiir vaterland. Cultur, 1858, Breslau. — Nageli, Sitzungsberichte der k. bayer. Akademie der 

 Wissenschaften, 1862, p. 233. — Cramer, Das Rhodospermin, in the seventh volume of the Viertel- 

 jahrsschrift der naturforsch. Gesellschaft in Ziirich.— J. Klein, Flora, 1871, No. ii. — Kraus, in 

 Jahrb. fUr wissensch. Bot. vol. VIII. p. 426. 



^ [The term ' crystalloid' is, in another portion of this work, used in a different sense, to express 

 any substance capable of crystallisation ; see Book III. Chap. i. Sect, i.] 



