ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 819 



formation, and the starting-point for the formation of other " products 

 of transformation." The cell-wall represents, as long as it is grow- 

 ing, a living memher of the cell. This is illustrated by the fact that 

 there are cells in which the greater part of the protoplasm is still con- 

 tained within the cell-wall, such as hypha) of fungi with thick-walled 

 growing ends. 



Development of Starch in Plants germinating in the dark.* — 

 M. E. Belzung gives the following as the general results of observations 

 on this subject : — 



Starch is always developed in the interior of leucites, and appears 

 in them shortly after their differentiation in the protoplasm. The 

 form of fully-developed leucites is nearly the same in all plants, viz. 

 almost spherical. When once differentiated leucites do not divide ; 

 they rapidly acquire a limited size, which they do not exceed. The 

 granules of starch which take possession of the leucites at the expense 

 of their albuminoid substances always remain extremely small. 

 When a plant developed in the dark is exposed to light, the green 

 matter is first of all fixed in the leucites which contain starch. It is, 

 therefore, formed from chloroleucites, which are, however, filled with 

 starch before the appearance of the chlorophyll. 



M. Belzung concludes that there are three kinds of starch, differ- 

 ing possibly in their physiological origin, viz. : — (1) Starch formed 

 in colourless or green leucites, with resorption of the substance of the 

 leucites, but without appreciable further growth (young plants, 

 leaves) ; these starch-granules are always small. (2) Starch formed 

 in colourless or green leucites, with complete resorption of the 

 leucites, and with further growth (cotyledons of the bean, haricot). 

 (3) Starch formed on the surface of leucites without apparent resorp- 

 tion of the leucites (Phajus). The last two kinds usually consist of 

 grains of large size with differentiated concentric layers. 



Soluble Starch, j — Dr. J. Dufour applies this term to a substance 

 which he finds chiefly in the epidermal cells of the leaves of Saponaria 

 officinalis, GypsopMla perfoliata, Bryonia clioica, Ornithogalum umhel- 

 latum, Arum italicum, species of Hordeum, and a few other plants 

 belonging to widely scattered orders among both Monocotyledons 

 and Dicotyledons. It is soluble in water and ordinary alcohol, much 

 less so in absolute alcohol, and only with difficulty in ether, benzine, 

 and chloroform ; acids and alkalies extract it rapidly, but without 

 any imbibition or swelling. Its most remarkable property is its 

 power of combining with iodine to a substance crystallizing in beau- 

 tiful blue needles, in addition to an amorphous condition. It crystal- 

 lizes also itself in the form of yellowish spherocrystals, varying in 

 diameter from 10 to 150 //., which polarize strongly. 



Dufour' s " soluble starch " occurs not only in the epidermis of the 

 leaves, but also in that of the stem and floral organs of Saponaria and 

 GypsopMla, in the former genus abundantly in the epidermis of both 



* Bull. Bot. Soc. France, xxxii. (1885) pp. 374 8. 



t Arch. BcL Phys. et Nat., xv. (1880) pp. 439-G5. Bull. Soc. Vaud. Soi 

 Nat,, xxi. (1886) pp. 227-GO. 



3 ii 2 



