. The cell in development and inheritance. Cells. I02 precisely like tliat ol iiuisclc-tibrcs ; aiul it is difficult to study Boveri's beautiful fii;ures and clear descriptions without sharing his conviction that "of the contractility of the fibrillce there can be no ; ^ \"ery cnn\ iiicini;- evidence in the same direction is afforded by pi^nient-cells and leucocytes or wandering cells, in both of which there is a \-ery large j^ermanent aster (attraction-sphere) even in the resting cell. The structure of the aster in the leucocyte, where it was first discove
. The cell in development and inheritance. Cells. I02 precisely like tliat ol iiuisclc-tibrcs ; aiul it is difficult to study Boveri's beautiful fii;ures and clear descriptions without sharing his conviction that "of the contractility of the fibrillce there can be no ; ^ \"ery cnn\ iiicini;- evidence in the same direction is afforded by pi^nient-cells and leucocytes or wandering cells, in both of which there is a \-ery large j^ermanent aster (attraction-sphere) even in the resting cell. The structure of the aster in the leucocyte, where it was first discovered by Flemniing in 1891, has been studied very carefully by Heidenhain in the salamander. The astral rays here extend throughout nearly the whole cell (Fig. 49), and are believed B A. \ -• ' Fig. 49. — Leucocytes or wandering cells of the salamander. [HEIDENHAIN.] A. Cell with a single nucleus containing a very coarse network of chromatin and two nucleoli (plasmosomes) ; s. permanent aster, its centre occupied by a double centrosome surrounded by an attraction-sphere. B. Similar cell, with double nucleus; the smaller dark masses in the latter are (linin), the larger masses are basichromatin (chromatin proper). by Heidenhain to represent the contractile elements by means of which the cell changes its form and creeps about. A similar con- clusion was reached by Solger ('91) and Zimmermann ('93, 2) in the case of pigment-cells (chromatophores) in fishes. These cells have, in an extraordinary degree, the power of changing their form and of actively creeping about. Solger and Zimmermann have shown that the pigment-cell contains an enormous aster, whose rays extend in every direction through the pigment-mass, and it is almost impos- sible to doubt that the aster is a contractile apparatus, like a radial muscular system, by means of which the active changes of form are produced (Fig. 50). This interpretation of the aster receives addi- tional support throug
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1906
