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Eine Methode zur kolorimetrischen Bestimmung der Wasserstoffionenkonzentration in pflanzlichen Gewebeschnitten ohne Anwendung von Moderatoren
morphological nature. The author believes that the chromatin of plants is a v~cuolated substance like the cytoplasm, and that there are no such structures as chromomeres upon a linin thread. This last statement is a very fundamental and far reaching one and leads to the conclusion thai "theories (pertaining to the arrangement of genes) which cannot be reconciled with a vacuolated structure of the chromosome will have to be abandoned." The author's findings are all the more interesting since, though based on fixed and stained plant material, they agree fully with observations on living animal material. There is so often a tendency for workers on fixed material to describe a s " g r a n u l a r " a structure which is alveolar in the living state. The alveolar structure which Bfitschli described, and which has to a great extent been unjustly criticized, is typical of many kinds of protoplasm but it is not of "universal" occurrence as Bfitschli assumed. Furthermore, the alveolar structure, which is simply that of an emulsion, is not the ultimate colloidal structure of protoplasm; the visible emulsmn is not the seat of such fundamental physical p r o p e r t i e s of p r o t o p l a s m as elasticity and imbibition. W e have io protoplasm, as in milk, a visible emulsion the dispersion medium of which is a lyophilic colloid, and the latter system is fundamentally different from the former. When protoplasm coagulates, just as when milk coagulates, the visible fat emulsion plays no active part; it is the protein content which coagulates, and the structure of elastic proteins is not that of a liquid suspension but of an interlacing mass of fibers, colloidal o r molecular. These facts in no way weaken the argument of Professor Chamberlain. The alveolar structure which he describes is a real one that plays its part in natural phenomena. Its presence in chromosomes undoubtedly necessitates a modification of the theory of the linear arrangement of genes. But the alveolar structure is not the one in which the physiologist is primarily interested in his search for an understanding of the dynamics of such vital processes as imbibition and permeability, nor is it the ultimate seat of the mechanism of heredity. W i l l i a m S e i f r i z (Philadelphia, Pa.).
Auf Grund seiner Anschauungen fiber das Wesen des Protoplasmas als ether Verbindung yon EiweifikSrpern mit Lipoiden betrachtet L; die roten