Lectures on the physiology of plants . ula-tion take place even in profound andcontinued darkness, and likewise incoloured light, and that by illumina-tion under the microscope at least nostriking change is undergone, is wellknown ^, although this does not ex-clude the possibility that more exactstudies in this direction may demon-strate an irritability to variations inthe light. Considering the great sen-sitiveness of swarm-spores and plas-modia for light, it is hardly crediblethat the protoplasm within the cellsshould be indißerent towards it; more-over all heliotropic organs, which arethus
Lectures on the physiology of plants . ula-tion take place even in profound andcontinued darkness, and likewise incoloured light, and that by illumina-tion under the microscope at least nostriking change is undergone, is wellknown ^, although this does not ex-clude the possibility that more exactstudies in this direction may demon-strate an irritability to variations inthe light. Considering the great sen-sitiveness of swarm-spores and plas-modia for light, it is hardly crediblethat the protoplasm within the cellsshould be indißerent towards it; more-over all heliotropic organs, which arethus sensitive to light, of course con-tain protoplasm in their cells, andwe have every reason to believe thatthe light-stimulus in heliotropic organsaffects principally their protoplasm,and that the corresponding alterationsin the cell-walls are initiated by is thus obvious (and the reason-ing applies to geotropic organs also)that all protoplasm enclosed in cellsis irritable to gravitation and light,only of course in a manner not. Fig. 361.—Optical lonsfitudinal section of the middle cell ofhair of the Gourd (from the calyx of a young flower-bud). Cell-wall simply in outline—the fine granules in the protoplasmdrawn too coarse. The central vacuolated clump encloses thenucleus of the cell. The streaming filaments, everywhere inactive movement, carry chlorophyll-corpuscles (containingstarch) in their substance: at one place (to the left) a crystalis also carried along. In rhe Bot. Zeitg. 1863 (Supplement, p. 3) I stated that the protoplasm ciiculates even in thecells of etiolated organs, e. g. hairs of Cucurbita: in fact, I prefer to employ wholly or partiallyetiolated plants for the demonstration of protoplasmic movements, on account of several advantages. CIRCULATION AND ROTATION OF PROTOPLASM. 617 directly perceptible by means of the microscope : moreover it need not be simplyin an alteration in the circulation and rotation that the irritability of the proto-plasm to g
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectplantph, bookyear1887
