230 



ANIMAL PHYSIOLOGY. 



[LESSON 69. 



FIG. 858. 



we find an approximation to the structure (ultimate) of muscular 

 fibre (Fig. 354). The plant consists, like all the algae, of a congeries 

 of cells of exceedingly variable size, depending upon their maturity. 



1020. A bud is shown, made up of cells equally variable in 

 size. In the interior of all these cells, without exception, is a nu- 

 cleus, of a reddish brown color, always bearing a close relation to 

 the size of the cell containing it (a). 



1021. In another marine alga, from the Island of Barbadoes 

 (Fig. 357), we appear to be gazing upon a very highly magnified 

 ultimate fibre of the Pig. The arrangement of the longitudinal 

 lines, indicating ultimate fibrillse, is perfect, and the cells, somewhat 

 longer in one diameter than in the transverse one, and containing 

 the (as if) sarcous elements (a), renders the illusion as satisfactory 

 as can well be desired. 



1022. But a still closer approximation is in store for us ; in 

 Lake Michigan, at Chicago, may be found, in great abundance, a 

 remarkably delicate fresh-water alga. Like all its kindred, it ex- 

 hibits, at the same moment, 

 every stage of development. 

 Small, detached portions of 

 this plant are extremely grace- 

 ful in the general arrangement 

 of their parts, as will be seen 

 by reference to the figure (Fig. 

 358). 



1023. This plant, collected 

 in the height of summer, gave 

 indication of its amazingly ra- 

 pid growth, all the cells, devoid 

 of nuclei, indicating new cells ; 

 the cells of the stem, how- 

 ever, are more mature than 

 those of the branches, and 

 each one contains a nucleus 

 (a). 



1024. It is only necessary 

 to refer the reader back (Fig. 

 354) to the highly magnified 

 view of the ultimate fibrilla 

 of muscular fibre, and making 



Alga from Lake Michigan, Chicago. due allowance for the dig . 



