178 E. A. Schäfer, 



I do not propose in the present article to give a complete or 

 monographic account of the structure of muscle, but rather to present 

 a critical review of the present position ot the question and to add 

 such new facts and observations as may throw light upon obscure 

 and disputed points in connexion with it. 



The present position of the question. 



The appearances of cross-striated muscle have of late been so 

 carefully investigated, both in the living condition and after death, 

 or after the action of reagents, that they may be taken to be well 

 ascertained so far as they are revealed by the optical appliances of the 

 present day. If the representations of living insect-muscle here given 

 (Fig. 1 A, which is reproduced from the Philosophical Transactions of 

 1873, and Fig. 5 A and C) are compared with those given \yy Eollett 

 (Denkschriften der Kaiserlichen Akademie, Wien 1885. Tafel IV. Fig. 21, 

 and 1886, Tafel I. Fig. 15) and by Ramon y Cajal (International 

 Journal of Anatomy and Physiology, Vol. Y. Plate XIX. Figs. 1 and 2), 

 it is at once evident that the same appearances are reproduced in all. 

 The same identity is evident in the representations of the transverse 

 section of Dytiscus muscle (compare Fig. 2, which is also reproduced 

 from the Philosophical Transactions of 1873 and Fig. 16, with Fig. 1. 

 Tafel. I of the Biologische Untersuchungen of Gr. Eetzius 1881; with 

 Fig. 6. Tafel I of the above quoted paper by Rollett, 1886; and with 

 Fig. 79 of van Gehuchten in La Cellule, Tome II, 1886). It is further 

 evident in the transverse views of muscles from other Arthropods and 

 Vertebrates (compare Fig. 15 with Retzius, op. cit. Tafel II. Fig. 41; 

 Rollet, Wiener Denkschriften, 1885, Tafel III. Fig. 18«, and 1886, 

 Tafel I. Figs. 1 to 4; and various figures given by van Gehuchten, 

 op. cit. and in a second paper La Cellule, Tome IV, 1888), and also 

 in the longitudinal views of acid-prepared and gold-stained fibres, which 

 abound in all the more recent of the above quoted articles and in 

 many others of the last few years, such as those of Bremer, Melland 

 and Marshall. 



That there are certain minor differences between some of the 



