Microscopical Society of London. 855 



might be alarmed, and make its escape before it could be pounced 

 upon by its unsuspected enemy. 



Another paper, by Edwin J. Quekett, Esq., entitled Remarks re- 

 lating to the Examination of Guano by the Microscope, was read. 



The author commenced by stating, that in consequence of the con- 

 stant adulteration of Guano, he was induced to seek some means by 

 which the genuine might be easily distinguished from the adulterated, 

 without the necessity of the lengthened and expensive process of 

 chemical analysis ; and he had endeavoured to make the microscope 

 the means of effecting this object. Viewed as an opaque object, 

 Guano appears to consist of particles of an earthy-brown colour, 

 mixed with crystalline bodies of various sizes, some of which appear 

 to be particles of sand, and others to be crystals of salts, of some 

 kind. The proportion of this crystalline matter to the brown amor- 

 phous substance, differs according to the locality whence the Guano 

 has been procured ; so that the Ichaboe Guano may be readily distin- 

 guished from the Peruvian, the former having much more of the crys- 

 talline matter than the latter. It however happens, that the good- 

 ness of the Guano does not depend on the presence or absence of this 

 crystalline matter, and consequently it forms no criterion of its value. 

 But although the microscope will not enable us to determine accu- 

 rately the value of that substance, it is quite capable of determining 

 whether it has been adulterated with foreign matters or not. Upon 

 viewing it as a transparent object, the nature of many of the bodies 

 composing it becomes apparent; and it is found to consist of organized, 

 crystalline, and mineral matters. The organized appear to be frag- 

 ments of dried flesh, either of birds or fish, minute fragments of shells, 

 spicula of sponges, and (especially in that from Ichaboe) many spe- 

 cimens of animalcules of various kinds. The crystalline and mineral 

 substances are found not only in the mass, but also occupying the 

 place of the medullary canal of bones ; the bones themselves having, 

 in most cases, been destroyed by decomposition. By analysis, the 

 crystalline matter is found to be composed of sulphate of potass and 

 ammonia. Mr. Quekett then entered into the investigation of the 

 probable sources whence these various substances may have been 

 derived ; and came to the conclusion that they are furnished either by 

 the dead bodies of the birds themselves, or from the substances 

 upon which they have fed remaining in a half-digested state in the 

 excrementitious matter of which the great mass of the Guano is 

 composed. J. W. 



