EFFECT OF CHANGES OF TEMPERATURE. 333 



Zoological Garden at Paris acquire during the winter a 

 woolly wad, like cow's hair. In a cooler climate, as that of 

 the Pamir, the goat and dog are covered with a tufted 

 fleece. This peculiarity seems to be hereditary in the An- 

 gora varieties of the she-goat, shepherd dog, and cats of 

 Angora (Angourieh) in Anatolia, the thickness of the fleece 

 being attributed to the severity of the winters (Cuenot). 



Wallace states that the varieties of bullfinches peculiar 

 to the Azores are undoubtedly the result of climatic and 

 other conditions operating through a long period. The 

 silvery feathers of the guinea hen are after transportation 

 to Europe transformed into long plumes. 



The white feathers and fur of arctic birds and mammals 

 are the result of adaptation to a cold, snow-clad region, and 

 these animals are evidently descended from tliose with 

 varied or darker colors. In the marsh-tit of Europe in 

 warm, rainy regions the brown is intensified ; in dry, sandy 

 districts the plumage is paler; in the arctic regions it varies 

 in paleness, and in Kamschatka it is almost white (Dixon). 

 Pallas states that not only timid and also predaceous ani- 

 mals in Siberia tend to become light-colored in winter, 

 but also domestic cattle and horses. 



Annual Variation. — The darter of Turkey Lake, Ind., 

 has been found by Moenkhans after an examination of 600 

 specimens to probably vary with the varying conditions 

 of successive years. Tlie first-year specimens wore the 

 exact duplicates of the third-year specimens, while the 

 second-year ones were quite different, these having two 

 more scales in the lateral line, and each 14 instead of 15 

 dorsal spines, the number in the first and third year's 

 specimens. 



Seasonal Dimorphism. — By subjecting the chrysalids of 

 lowland butterflies to prolonged cold in icehouses Weis- 

 mann has proved that northern and alpine species are 

 climatic or seasonal varieties or forms of such insects. 

 W. H. Edwards has shown that two of the four polymor- 

 phic forms of Papilio ajax {i.e., walsldi and telamonides) 



