Show I The Skins of Birds A writer in the Scientific American t says In collecting bird skins I have found innumerable air cells forming a most delicate and wonderful network between the body and the skin In Inthe Inthe Inthe the pelican one of our largest birds this network of cells practically covered covered cov cov- ered the whole body and was very noticeable Now if those cells work automatically like the lungs or like the circulation of the blood being filled filled fill fill- ed with or emptied of hot air according according accord accord- ing to the purpose of the bird to rise float or descend then surely we can I 1 better understand the ease with which birds seem to sustain themselves themselves them them- r i selves In the air during their long ij flights |