CHAPTER V. 



THE MUSCLES; THE FAT-BODY AND CCELOM. 



SPECIAL REFERENCES. 



VIALLANES. Histologie et Developpement des Insectes. Aun. Sci. Nat., Zool., 

 Tom. XIV. (1882). 



KUHNE in Strieker's Histology, Vol. I. , chap. v. 



PLATEAU. Various Memoirs in Bull. Acad. Roy. de Belgique (1805, 1866, 1883, 

 1884). [Relative and Absolute Muscular Fo7~ce.] 



LEYDIG. Zum feineren Bau der Artliropoden. Miiller's Archiv., 1855. 



WEISMANN. Ueber zwei Typen contractilen Gewebes, &c. Zeits. fur ration. 

 Medicin. Bd. XV. (1862). 



Structure of Insect Muscles. 



THE muscles of the Cockroach, when quite fresh, appear 

 semi-transparent and colourless. If subjected to pressure or 

 strain they are found to be extremely tender. Alcohol hardens 

 and contracts them, while it renders them opaque and brittle. 



The minute structure of the voluntary or striped muscular 

 fibres of Vertebrates is described in common text-books.* Each 

 fibre is invested by a transparent elastic sheath, the sarcolemma, 

 and the space within the sarcolemma is subdivided by trans- 

 verse membranes into a series of compartments. The com- 

 partments are nearly filled by as many contractile discs, 

 broad, doubly refractive plates, which are further divisible 

 into prismatic columns, the sarcous elements, each being as 

 long as the contractile disc. Successive sarcous elements, 

 continued from one compartment to another, form the 

 primitive fibrils of the muscle. In cross-section the fibrils 

 appear as polygonal areas bounded by bright lines. Outside 

 the fibres, but within the sarcolemma, are nuclei, imbedded in 

 the protoplasm, or living and formative element of the tissue. 



* See, for example, Klein's Elements of Histology, chap. ix. 



