BIOLOGICAL AND MICROSCOPICAL DEPARTMENT. ( J 



October Sd, 1870. 



Director 8. W. Mitchell, M. I)., in the Chair. 



Thirteen members present. 



The report of the Committee upon the Myiarchm cinerascem was 

 presented, as follows : 



The Committee to which was referred the specimen of Myiarchm cineri 

 cms vel Mexicanus, with 'fungous growth of its feet,' forwarded for investiga- 

 tion from the Smithsonian Institution of Washington, report that, although 

 the great changes which have taken place in the abnormal formation bv 

 drying render it impossible to determine with certainty its nature during the 

 life of the bird, they have been able to recognize the following characteris- 

 tics : Examined with a hand magnifying glass, the adventitious struc 

 was found to be porous, and to present a cellular appearance closely resem- 

 bling that of a section of mammalian lung which had been inflated and dried. 

 A thin slice immersed in liquor potassa or glycerin and examined with a 

 power of 200 diameters, was seen to be composed of bands of material resem- 

 bling fibrous tissue, arranged so as to form alveoli, each about 1-1 50th of an 

 inch in diameter with a wall of l-600th of an inch in thickness. These alve- 

 oli frequently contained mycelial threads, apparently of some fungus of the 

 Leptothrix type, and occasionally portions of Acari, resembling the A. Sea- 

 bseii, with their ova and excrement. It seemed improbable that this patholo- 

 gical product was the result of the integument covering the legs and feet, and 

 bearing even a fanciful analogy to the Elephantiasis of human bi ii gs : first, 

 because a transverse section of one of the toes showed the black scaly skin 

 apparently unaltered beneath the fungous growth, which was readily peeled 

 off; second, because it covered the rather elongated claws of the bird with as 

 thick and firm a coating as that found upon the adjacent portion of the toes 

 supplied with its modified cuticle ; and thirdly, from the absence of epithelial 

 or other similar cells in the sections examined, even with a high power (1200 

 diam.) Any hypothesis of its being a malignant growth springing from the 

 connective tissue beneath the integument was likewise deemed untenable, 

 not only on account of the circumstances just enumerated, but also because 

 the disease was so symmetrically developed upon both lower extremities ; 

 and vour Committee was therefore, with some hesitation, led to assume that 

 the growth was really of a fungous nature, and perhaps bore some slight re- 

 semblance to those comparatively rare affections of our race, Favm and Tinea 

 tonsurans of the nails. The only fact which militated strongly against this 

 view was that, on burning a small fragment of the abnormal structure in the 

 flame of a spirit lamp, a decided animal odor was evolved, and a faint cloud 

 of ammonic-nitrate appeared when the smoking particle was brought in con- 

 tact with the vapor of nitric acid. Even this might be readily explained by 

 the existence in the mass of the various animal excretions with which such a 

 dense covering would probably be charged. 



All of which is respectfully submitted, 



(Signed) Jos. G. Richardson, 



Sept. 23d, 1870. Harrisox Allen. 



On motion, the report was accepted, the Committee discharged, 

 and the Corresponding Secretary directed to transmit the document 

 to the Smithsonian Institution. 



A communication was presented from Prof. Baird, of the Smith- 

 sonian Institution, accompanied by a specimen of finely pulverized 

 material stated to have fallen in a dust shower over portions of 

 Vermont ; to examine which Drs. J. G. Hunt and William Corbit 

 were appointed. 



