260 POUCHET, OX ATMOSPHERIC CORPUSCLES. 



these situations the corpuscles, once introduced, escape only 

 with great difficulty, owing to the immobility of the Avails 

 and the irregularities of their anfractuositics, we there find 

 ample vestiges of all the matters conveyed by the air into 

 the respiratory organs. 



The examination of animals living in the midst of towns, 

 and in the interior of our dwellings, will excite surprise by 

 the enormous quantity of starch-grains contained in their 

 respiratory organs. In birds, corpuscles of this nature will 

 be discovered in great abundance, even in the interior of the 

 bones, and together with them will be observed, in profusion, 

 particles of sooty matter and filaments derived from the 

 various fabrics of which our clothes are made. But the fur- 

 ther the creature lives from towns, the more remote and 

 wild its habitation, the more rare also become all these cor- 

 puscles in the inspired air. Under these circumstances, 

 scarcely any traces of the sort can be observed. Fre- 

 quently, even not a single particle of the kind in question 

 w r ill be observed in animals or birds living altogether in the 

 midst of forests ; in these animals, on the other hand, the 

 whole respiratory apparatus is filled with abundant debris of 

 plants, — epidermis, chlorophyll, &c. 



The amylaceous particles disseminated either in the atmo- 

 sphere or in the interior of animals present two conditions — 

 they are either in the normal state or cooked. In the 

 majority of cases the starch is found in the former condi- 

 tion; but, nevertheless, we frequently meet, in the atmo- 

 sphere, and in all the cavities of animals into which the air 

 enters, with starch-grains, either simply swelled or entirely 

 burst by the action of heat. The latter certainly proceed only 

 from minute particles of bread carried about by the move- 

 ments of the atmosphere. This panified starch is readily 

 recognised by its enormous size and ruptured condition, and 

 by the action of iodine, which does not produce in it the 

 same bright colour as it does in ordinary starch-grains. 



The birds which inhabit the interior or lire in the close 

 vicinity of towns do not obtain this abundance of amyla- 

 ceous particles simply from the air they inspire; they derive, 

 besides this source, an abundant supply from the foliage of 

 the trees amidst which they pass part of their lives. In 

 fact, on examining the surface of the leaves of trees in the 

 neighbourhood of cities, when they have not been washed for 

 some days by rain, abundance of specimens of every sort of 

 corpuscles carried in the atmosphere will be found on them, 

 and, universally, a considerable quantity of starch-grains, 



together with sooty and siliceous particles. On a single leaf 



