. Anatomischer Anzeiger. Anatomy, Comparative; Anatomy, Comparative. 521 and contracted phases. Camera-lucida drawings, however, of a single chromatophore, showed that after a contraction of twenty hours, the processes had not been changed in any way; the expanded chromato- phore had the same contour as before the contraction (Textfig. 1, a-c, p. 23). Kahn und Lieben (:07) made series of consecutive photographs of single melanophores in the web of the frog's foot (R. temporaria). These cells Avere first photographed in the expanded condition; they were then contracted by an intra-venous or int
. Anatomischer Anzeiger. Anatomy, Comparative; Anatomy, Comparative. 521 and contracted phases. Camera-lucida drawings, however, of a single chromatophore, showed that after a contraction of twenty hours, the processes had not been changed in any way; the expanded chromato- phore had the same contour as before the contraction (Textfig. 1, a-c, p. 23). Kahn und Lieben (:07) made series of consecutive photographs of single melanophores in the web of the frog's foot (R. temporaria). These cells Avere first photographed in the expanded condition; they were then contracted by an intra-venous or intra-peritoneal injection of adrenalin (Lieben : 06), again photographed, and, after recovering from the effect of this contracting stimulus, the re-expanded melano- phores showed pre- cisely the same con- tours as in the first expanded phase. Altho these observa- tions proved conclu- sively that the mela- nin granules migrate along fixed paths, Winkler (: 10), after a series of experi- ments with Hyla ar- borea, seemed in- clined to revert to the older view of FiCALBi ('96), who believed that the chromatophores have the power of sending out new processes which are independent of the preformed paths. Winkler used galvanic and induced currents as expanding and contracting stimuli. Under these circumstances he observed that the original pro- cesses did not reappear in every case. He finally concluded that the pigment in general follows fixed processes but that it is not forced to do so, for, under the influence of the galvanic current, processes appear in places where previously none had been visible. There is a serious objection to this conclusion. If the pigment does not always reappear in the old processes, there is no proof whatever that what Winkler regarded as new processes brought about by the galvanic current, were not actually old ones in which the granules had simply failed to appear at the previous Fig. 1. A group of melanophores which have been expanded in
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherjenag, bookyear1913
