General principles of zoology . homogeneity, have avery extraordinary diversity. For if we see that from theegg of a dog there comes always and only a dog, and in-deed an animal with all his individual peculiarities, that asea-urchins egg, placed under the most diverse condi-tions, produces always a sea-urchin, that a species ofamoeba always performs only the movements characteristicof that species, we must assume that the functioning con-stituent part of this cell, the protoplasm, has in each caseits peculiarities. We are driven to the assumption of analmost unlimited diversity of protoplasm,
General principles of zoology . homogeneity, have avery extraordinary diversity. For if we see that from theegg of a dog there comes always and only a dog, and in-deed an animal with all his individual peculiarities, that asea-urchins egg, placed under the most diverse condi-tions, produces always a sea-urchin, that a species ofamoeba always performs only the movements characteristicof that species, we must assume that the functioning con-stituent part of this cell, the protoplasm, has in each caseits peculiarities. We are driven to the assumption of analmost unlimited diversity of protoplasm, even if \ve con-cede an important share in the prominent differences to thenucleus, of which we shall speak later. General Properties of Protoplasm.—The similarity ofprotoplasm, still recognizable through all its variations, ex-presses itself in its appearance and in its vital slight magnification, protoplasm appears as a faintly-gray substance, sometimes colored yellowish, reddish, etc., GENERAL ANATOMY. 75. by pigments taken up by imbibition, in which numerousstrongly - refracting granulesare embedded. The vital char-acteristics of this substanceare movement, irritability,power of assimilation and ofreproduction. Movement of Proto-plasm.—Movement expressesitself firstly in changes of formof the whole body—amoeboidmovement—and secondly inthe change of position of thesmall granules in the interiorof the protoplasm—stream-ing of grannies. Examples ofamaiwid movement (Fig. 16) FlG. proteus. (After ; 1 • a ,, ,-,4-0 ^( fk, ectosarc ; en, entosarc ; cv, contractile are chiefly the movements ot Vacuoie; «, nucleus; ^, protozoa, and of the colorless blood-cells (white blood-corpuscles) of multicellularanimals; here the protoplasmic body sends out coarser projections, which may be again withdrawn, servingfor locomotion and hence called pseudopodia or false streaming of granules can be observed i
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1896
