Proceedings of the Royal Society of Victoria (New Ser. V. 4)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1896 Excerpt: ...that the temperatures had the wide range that lies between 12 and 32. The lizards appear to be colder a little than the air. This I believe to be due only to the fact that, taking temperatures before eight o'clock in the morning, the lizards were still considerably in the rear of the air temperature, while between five and six o'clock in the evening, though they were above the air temperature, the excess then did not wholly balance the morning deficiency. I am convinced that if one took the temperature of a quiet lizard every hour for a month, the average would correspond almost exactly with the average temperature of the air. The morning and evening observations which I took would give a less exact result, though from them the difference is only three-tenths of a degree. A cold-blooded animal is therefore one which when at rest takes its temperature almost absolutely from its environment. When a snake is asleep, the slow beat of its heart, eight or ten times in a minute, will generally, so far as I have noticed, keep the muscles of the heart itself about six or eight tenths of a degree warmer than the rest of the body. This, diffused through the whole body, must have a tendency to slightly increase its temperature, but only to a minute extent. The same snake, however, after a time of activity may be two or three degrees above the heat of the surrounding air. Yet even that is inconsiderable compared with the extreme rise and fall of the creature's temperature with the alternations of day and night, of hot or cold weather. The steps whereby the more active and intelligent warmblooded types have arisen from this lethargic level would form a fascinating subject for enquiry, but I purpose here only the much easier and more prosaic one of recording that such ste...