yO Bulletin Wisconsin Natural History Society. [Vol. 7, Nos. 3-4. 



Attention was called to the prevelance of white pelage and plumage 

 in the Arctic region where is served not only a protective or aggressive 

 role but also subjected the animals to less loss of bodily heat by 

 radiation than would darker colors. 



Various examples of dichromatism, the grey squirrel, leopard, red- 

 dish egret, screech owl, etc., werg mentioned and a number of speci- 

 mens illustrative of both albinism and melanism were exhibited. 



Dr. George P. Barth then took up the subject of albinism and 

 melanism in man. He spoke of the normal occurrence of melanin in 

 the human tissues and mentioned Abel and Davis' calculations of the 

 quantity of melanin in the negro's skin and hair (1 gram) as opposed 

 to the enormous quantity found in some pathological growths (300 

 grams having been recovered from a melanotic sarcoma of the liver.) 

 He touched slightly on the chemistry of the melanins and quoted Von 

 Fiirth's theory of its formation, to-wit: Melanin and the melanoid 

 bodies are developed by the action of intracellular oxidases (tyrosi- 

 nase'; upon the aromatic or chromagen groups of the protein molecule. 

 A physiological increase is present in certain conditions. 



Dr. Barth then went into the experiments of Loeb on the trans- 

 plantation of both pigmented and unpigmented skin grafts to denuded 

 areas which proved that in no case is the skin of another species found 

 to be successfully grafted in man ; in all cases the cells undergo 

 necrosis. Homotropism, an attraction of cells to others of a like 

 order, or a chemotropism may account for the greater rapidity with 

 which a denuded surface is covered by new skin after a graft. 



Albinism is merely the lack of the presence of the coloring matter 

 melanin in the tissues. It is always present at birth and therefore 

 inherited ; but as to whether it has any value in supporting theories of 

 heredity or of Mendelism is not established, as no observations have 

 been made with this object in view. It may have the same value as 

 certain other conditions often transmitted to offspring such as poly- 

 dactylism, absence of parts, peculiarity of features, etc. 



In conclusion, Dr. Barth discussed briefly the symtomatology of 

 albinism and disease vitiligo. 



Dr. Graenicher instanced the occurrence of albinic and melanic 

 forms in field clover. 



Reproduction was informally discussed by the following members: 

 Messrs. Carpenter, Mann, who related his experiences in breeding foxes, 

 Ward, Whitnall, Muttkowski, and Colles. 



Upon motion the meeting then adjourned. 



