35° 



MY GARDE AT. 



diatomes agree in having a silicious skeleton. This skeleton has been 

 more observed than the organism itself, and there are many 

 microscopists who devote their time to the observation of the beautiful 

 marking on this silicious body. Mr. Miiller, a German, sells as an 



Fig. 808. — Epithemia turgida^ Fig. 809. — Surinella biscriata, \ 



X 200 diam. x 200 diam. ^ 



Fi& 810. — Cocconema Flc. 811. — Pinnularia 

 lanceolatum- x 200 diam. major, x 200 diam. 



article of commerce a microscopic slide containing four hundred of 

 these silicious particles for four guineas, which is perhaps one of the 

 most marvellous feats in microscopical manipulation which has ever 

 been accomplished. Mr. William Thornthwaite has 

 particularly examined the diatomes in my garden, 

 and has noticed about fifty species. 

 f Every season seems to have its 



^ particular variety, which comes and 



I f passes away with great rapidity. As 



the plant life of these vegetals is 



Fig. 8i2.— Cymelopleura Flo. 813.— Pleurosigraa 

 solea, X 200 diam. attenuatum, x 200 diam. 



Fig. 814. — Campylodiscus spiralis, 

 X 200 diam. 



quite unknown, and as the cause for the variation in the form and 

 figure of the silex is equally unknown, the study of the diatomes 



