Age and Resistance to Ether in Mice

Abstract

Wide variations have been observed in the length of time necessary to anesthetize mice by means of ether. Active adults as well as old and rather feeble animals reacted in perhaps one-tenth of the time of young a week or less in age. Two groups of mice were available for testing this observation, and a series of experiments was made with each group.

The first of these groups (here designated the K Strain) was a genetically heterogeneous lot, containing various combinations of the following mutant types: chinchilla, extreme-dilution, albinism, white-bellied-agouti, non-agouti, brown, short-ear, piebald, silver, dwarf, flexed-tail, and several new types of which the genetics is not fully worked out. A number of these mice were from the stocks of Dr. G. D. Snell of the University of Texas, to whom the author is greatly indebted for assistance in many ways. The second group (here designated the Inbred Strain) was, on the other hand, relatively homogeneous genetically, as a result of some 25 generations of inbreeding, and contained only the wild agouti type. These mice were kindly sent to the author by Dr. L. C. Strong of the Roscoe B. Jackson Memorial Laboratory, Bar Harbor, Maine.

The apparatus consisted of several 3-liter flasks with rubber stoppers; fresh “Ether Squibb”; a graduated pipette; platform scales; thermometer. The procedure was as follows: Into one of the flasks at room temperature (23°-26°C.) was introduced 2.4 cc. of liquid ether, which was allowed to vaporize while the stopper was loosely in place. Then with the stopper tight, the flask was inverted for one minute, after which it was allowed to stand for a further 10 to 15 minutes, when the temperature within the flask was about 2° lower than room temperature.