On the Relation of the isotropous to the anisotropous Layers in striped Muscles. 541 



compelled to fly about a nearly empty room. In a few minutes they 

 dropped down exhausted, so that no pushing or handling could induce 

 them to fly. They were instantly killed in boiling water, cut down 

 the back with a razor, and plunged into Flemming's fluid, a fresh 

 fly being at the same time similarly treated. The further processes 

 of staining, washing out, embedding «S;c. were as nearly as possible 

 the same for both. From many comparisons of these exhausted wing 

 muscles with the homologous muscles in the untired flies I invariably 

 obtained the same result, which I have embodied in the drawing 

 (Fig. 25 Ä and B). The enormous swelling of the sarcosomes must 

 not detain us here. The point which here interests us most is the 

 complete absence in the exhausted muscle of anisotropous zones and 

 of any diiferentiation by means of stains. While in the fresh fibre, 

 the anisotropous areas are clearly discernible, in the tired muscle the 

 stain is difl'use, pervading not only the whole fibre, but also the 

 enlarged sarcosomes. 



It must however remain an open question whether we can con- 

 clude from this disappearance of a distinct anisotropous layer a using 

 up of the anisotropous substance. We are, however, justified in con- 

 cluding that the capacity for contraction is in some way due to the 

 differentiation of the layers, and that the fibril can no longer function 

 when that differentiation disappears. This is so much evidence in 

 favour of the mixture of the two substances above suggested as being 

 the essential element in muscle contraction. 



Looking then for other evidence, it is worth recording the well- 

 known fact that the anisotropous layers stain deeply with all ordinary 

 stains which stain the nucleus. Further, Altmann ^ ) has employed a 

 mixture of fuchsin which will not stain the nucleus, and which also 

 does not stain the anisotropous layers in muscle fibre. 



More striking evidence has however lately been given in favour 

 of the anisotropous layers being nuclear. As is well known, one of 

 the most remarkable features in nuclein is its large proportion of 

 phosphorus. The recent researches of Lilienfeld and Monti *) have 

 shown that the anisotropous layers are especially rich in phosphorus. 

 This, combined with the evidence, positive and negative, to be derived 



1) Die Elementar-Organismen und ihre Beziehungen zu den Zellen, 

 Leipzig 1890. 



2) Ueber die mikrochemische Localisation des Phosphors, in : Zeitschr. 

 Physiol. Chemie, Bd. 17, Nov. 1892, p. 423. 



