228 ANIMAL PHYSIOLOGY. [LESSON 68. 



The fibrilla will now appear to be a delicate transparent tube, divid- 

 ed by well defined but very delicate transverse lines, by which the 

 structure is broken up into a series of symmetrical cells. 



1009. In the centre of each cell is a solid, dark body the sarcous 

 element of Bowman. 



1010. A fourth object-glass will only show a single transverse 

 line; but a superior twelfth object-glass will show that the line is 

 double divided by the least conceivable interval of space. 



1011. If the structure be built up of cells (of which there ap- 

 pears no room for doubt), each cell should have an upper and lower 

 portion, and the approximation of two cells should show the top of 

 the one and the bottom of the other, and this is true. 



1012. The transparent membrane around the sarcous element 

 has been named the sarcolemma (sheath of the fleshy element). 



1013. Thus it will be seen that a primitive fasciculus is made up 

 of a number of fibrillae, running together in a longitudinal direction, 

 united together by areolar tissue ; when a fibre is formed, the entire 

 fasciculus is contained in the peculiar sheath, the myolemma. 



Each fibrilla is again composed, as before stated, of an external 

 tubular sheath, the sarcolemma, in which is contained cells having 

 rectangular discs (sarcous elements) enclosed in chambers, or spaces, 

 formed by processes of the sarcolemma extending across the tube. 

 The fasciculi are united in bundles by areolar tissue, invested by the 

 myolemma to form the fibres of descriptive anatomy. 



LESSON LXYIII. 



MUSCULAR FIBRE, CONCLUDED. 



1014. Such is the history of the structure of the muscular fibre 

 of animal life, and when compared with the representations of fresh- 

 water and marine algae, they will be seen to be identical. 



1015. Thus Fig. 355 represents a very beautiful parasitic fresh- 

 water Alga, found upon the stems and leaves of the white and yellow 

 pond-lilies. The entire structure consists of a congeries of square- 

 shaped cells, each of which is a plant in itself, and containing an 

 equally square nucleus, or germinal spot. 



1016. It should be remarked that the squareness of the cell, and 

 of the nucleus, form distinctive characters of this order of plants. 



