486 Miscellaneous. 



In the particles of silica placed upon the glass slide, when they 

 were completely separated from each other, the outlines of the indi- 

 vidual diatoms were sharply and distinctly defined. On the other 

 hand, when the physical action of ebullition with nitric acid was 

 not sufficient for the complete separation of the particles of the epi- 

 dermal shield, there was observed a marvellous interlacing of the 

 various forms, showing that they were conveyed by the sap-cells 

 directly to the section of the plant where they were destined to com- 

 plete its structure. I have examined several specimens of straw, 

 taken at random in the market : the silica in each specimen con- 

 sisted of plates, very thin and truncated at the corners. 



The result of these investigations shows the necessity of finely 

 divided silica in the soil, so minute as to be capable of passing with 

 facihty through the sap-cells ; secondly, that simple or compound 

 silicates are useless as fertilizing agents, either natural or artificially 

 prepared. We have no valid reason for forming any theory that 

 vegetation can, through any known chemical law, separate the ele- 

 ments or their compounds from combinations so positive in their 

 character. 



In this case we have a practical result, capable of being verified 

 at any stage of growth of a plant, produced by the application of 

 silica to the soil in the form of certain well-defined microscopic 

 organisms ; for, finding these in the ash to the exclusion of other 

 particles of silica, they seem to be more acceptable for the plant- 

 structure. Free silica is hence the only condition in which it can 

 enter the plant. 



I look upon this discovery as leading agricultural investigations 

 in a new direction ; and it must eventually change many of the views 

 expressed and accepted by scientists. 



Every precaution was used in having all the material thoroughly 

 cleansed, with a view both to accuracy and to removing suspicions 

 that these microscopic forms were the result of dust-showers. — 

 Sillimmi's American Journal, May 1876. 



• Washington University, Medical Department. 

 Baltimore, Md., February 1876, 



On Fish of the Ceratodus-group existing in the River Fitzroy, 

 South Australia. By M. Paul Gekvais. 



M. Paul Gervais announces that he has received from M. Francis 

 de Castelnau, French Consul at Melbourne, an intimation of the 

 existence in the river Fitzroy of a new form of fish allied to Cera- 

 todus. It presents the principal characters of the species from the 

 river Burnett, to which Messrs. Krefft and Giinther have given the 

 name of Ceratodus Forsteri, but difi'ers from them sufficiently to lead 

 M. de Castelnau to regard it as forming a distinct genus. He gives 

 the name of Neoceratodus to this genus, and calls the species 

 N. Blanchardi. — Comptes Bendus, May 1, 1876, p. 1034. 



