NATURE'S JEWELS. 165 



become surrounded by a gelatinous or mucous 

 matter which holds them together. The valves 

 of each Diatom now dehisce or gape, and the 

 endochrome, or cell contents, of each flows out 

 and mingle together, forming a globular mass, 

 which gradually assumes the parental form, only 

 much larger ; or the new body thus produced may 

 assume a form unlike that of its parents. In either 

 case, however, it is only transitional in its nature 

 or rather, it is the fruit or seed whence the new 

 generation is to spring. By-and-by, it will break 

 up or open, setting free the myriad brood of embryos 

 or gonidia, i.e., spores or buds, which " either remain 

 free or surround themselves with mucous, forming 

 a pellicle or stratum, and in a definite but un- 

 ascertained period reach the mature form," when 

 they become invested with the silicious valves and 

 zones, and consequently cease to grow or enlarge, 

 except by the process of division already described. 

 Something like an alternation of generations has 

 also been observed in some varieties, one form pro- 

 ducing buds, which in their development assume 

 forms unlike their parents, and these producing yet 

 other differing ones, which in their turn reproduce 



