POUCHET, ON ATMOSPHERIC CORPUSCLES. 



263 



The lungs of a Mouse also afforded starch, silex, and 

 soot, but in far less quantity and in far smaller fragments 

 than in the birds. 



But if our attention be directed to wild birds, residing at a 

 distance from cities, we observe a totally different thing. 



A Gray Falcon (Falco cineraceus, Mont.), killed in a large 

 forest two leagues from any habitation, did not afford the 

 least trace of starch, either in its air-passages or within the 

 bones. There were met with only a few particles of soot 

 and silex ; and not a single filament of any kind of tissue 

 was recognised. But, on the contrary, all the air- passages 

 were filled with an abundance of the detritus of plants and 

 debris of insects. 



In another wild bird (Picus viridis, Linn.) I found in 

 the air-passages only an insignificant quantity of starch, and 

 very little soot and silex. 



In some frogs taken in the basins of the Jardin des Plantes 

 at Rouen, which is situated close to numerous factories 

 and in a populous quarter, the lungs have always afforded 

 a notable quantity of starch, an abundance of particles of 

 charcoal and coal-soot, together with numerous fragments of 

 silex and vegetable debris. Besides these, filaments of cotton, 

 raw or manufactured, were extremely abundant. The respi- 

 ratory organs of these animals also contained Naviculce, 

 diatoms, papilionaceous scales, the stems of mucedinous fungi, 

 and fragments of Confervas. 



If, again, we explore the respiratory passages of some 

 animals which, although living in a state of liberty, are in 

 the habit of frequenting our dwellings, we find in them 

 evident vestiges of their double existence, wild and domestic. 



A Jackdaw afforded a striking instance of this. Its respi- 

 ratory organs contained a very considerable quantity of 

 wheat-starch ; and what was very remarkable, an enormous 

 number of sooty particles — a circumstance which is accounted 

 for by the almost habitual abode of this bird on the lofty 

 buildings of towns. There were found also, in its air-sacs, 

 numerous filaments of cotton and abundant debris of plants. 



In all my observations, which, without exaggeration, 

 might be counted by hundreds, I have never met with either 

 a single spore or a single ovum of a microzoon, nor Avith 

 any encysted animalcule. Moreover, if in all these minute 

 researches I have always been able to detect starch-grains 

 wherever they existed, is it possible that the atmospheric spores 

 and ova alone should have escaped detection? The ova of 

 certain Paramcecia, being -0420 mm. in diameter, and conse- 

 quently surpassing considerably in bulk the largest grains 



VOL. VIII. x 



