52 THE MICROSCOPE. Apr. 



and the mind too when it is properly used, more search- 

 ing. If we look in an encyclopaedia to see what guano 

 is, we find something like the following : We find that 

 it is the excrement of birds and other aquatic animals 

 that is found on the islands, more particularly in Peru 

 in the Pacific Ocean, reddish in color and smelling 

 strongly of ammonia and which is brought home by ves- 

 sels for the use of the farmer as a manure. It was 

 brought home by Humboldt in 1804, being found by him 

 at the Chincha Islands and was in use during the iVtli 

 and 18th centuries by the inhabitants of Peru. It was 

 analyzed by the German and French chemists Klaproth, 

 Fourcroy and Vauquelin. But it was not until the pub- 

 lication in 1840 by Leibig of his work on agricultural 

 chemistry that its uses in agriculture were proved. In 

 1850, no less then 500,000 tons were imported into Eng- 

 land from Lima and it sold at about £13 per ton. An in- 

 terest commercially in money value showed how impor- 

 tant it was. Now it is being exhausted and although 

 guano has been found elsewhere as at South Africa,^ 

 (hence the name Ichaboe) and in the mid Pacific and in 

 the Carribean sea it is now scarce to what it was. This 

 is all very fine commercially, but why does the micro- 

 scope turn to it to view it ? 



Some years since my attention was called to the sub- 

 ject of guano when engaged as an analytical chemist in 

 examining the fertilizers of different kinds and thereaf- 

 ter when studying the Bacillariacese (or Diatomacese, as 

 they are commonly but wrongfully called), and their ap- 

 plications to geology. At last I came to the conclusion 

 that the prevelant notion with regard to the origin of 

 guano was erroneous, for I wanted to find out the why 

 and wherefore for all things. That was my failing, if I 

 may call it so. My ideas of the subject were embodied 

 in a communication made to the Essex Institute of Sa- 

 lem, Mass., on the 4th of January 1869, an abstract of 



