閱讀難度：

Ever wonder how dogs can walk barefoot in the snow? Now a Japanese scientist may have the answer -- an internal central heating system, Reuters reported.

The secret lies in how dogs circulate their blood to prevent cold surfaces from chilling the rest of their bodies, according to Hiroyoshi Ninomiya, a professor at Yamazaki Gakuen University.

The system uses warm, oxygenated blood to heat the cold blood that has been in contact with a cold surface before returning it to the dog's heart and central circulation.

Dogs are not alone in having this sort of heat exchange system, which is shared by other animals such as dolphins, Ninomiya said. （點擊路透社網站查看原文）

為什么狗狗不怕冷？

???????可曾想過狗狗為何能光腳在雪地上行走自如？路透社報道稱，日本科學家可能已找到答案——因為它們的腳掌上有個內部中央加熱系統。

???????東京山崎學園大學教授二宮博義研究指出，奧秘之處在于，狗狗是如何使血液循環起來，以避免冰冷的地面導致身體受寒。

???????其實，這套機制是利用溫暖的含氧血液來為接觸冰冷地面的冷血液加溫，然后再將其送回心臟和中央循環系統。

???????二宮表示，狗狗并不是唯一擁有這種熱交換系統的動物，海豚等其它動物也具有該機制。

(China.org.cn March 8, 2012)