TRANSLATIONS. 



On the Multiplication and Reproduction of the Diato- 

 MACEvE. By the Conte Ab. Francesco Casteacane 



DEGLI AnTELMINELLI. 

 (From the 'Atti dell' Academia pontificia de Nuovi Lincei,' April 19, 1SG8.) 



The numerous improvements in the microscope, of late 

 years, have made us acquainted with an infinite number of 

 new forms belonging to the lower divisions of the vegetable 

 kingdom, and esjiecially to the Diatomacese, the known 

 number of which has advanced from the two or three species 

 which had been distinguished at the end of the last century, 

 to not less, according to Brebisson, than 2000 at the present 

 time. But however great this addition to the number of 

 facts serving to elucidate the natural history of these most 

 interesting organisms may have been, the same cannot, un- 

 fortunately, be said regarding our knowledge of their organic 

 development and general economy. This lamentable 

 condition of things must be attributed to the too natural 

 desire which observers entertain to associate their name with 

 the discovery of a new form, to which end, consequently, the 

 majority devote themselves. And an additional reason may 

 be found in the difficulties which are met Avith in the inves- 

 tigation of the mode of development of organisms of such 

 astonishing minuteness, w^hich renders it almost a matter of 

 chance when we are able to observe the various phases of the 

 organic life of the Diatomaceae. Whence arises the necessity 

 of examining Avith the utmost attention everything that is 

 presented in the field of the microscope, and especially in the 

 case of living diatoms, which should be daily observed at all 

 seasons to enable us to watch all the epochs of their develop- 

 ment. 



The apparent function of the Diatomaceaj in the economy 

 of nature, viz. to vivify, as it were, the immensity of the 

 ocean, as well as all fresh and brackish Avaters, decomposing, 

 as they do, carbonic acid under the influence of light, and 



