Parabiotic Twins as a Means of Determining Cellular Individuality. ∗

Abstract

It has been shown 1 that a division of species-specific substances of the erythrocytes of Pearlneck (Spilopelia chinensis), not present in those of Ring dove (Streptopelia risoria), is found in the progeny of male hybrids backcrossed to Ring dove. Individual differences in the cells of these backcross birds make reasonable the conclusion that many different heritable cellular components distinguish Pearl-neck from Ring dove. It seemed opportune to test whether or not a successful “take” of parabionts in backcross hybrids depends, at least in part, upon the relative number of such Pearlneck substances in one member of the pair as contrasted with their absence in the other. The appearance of antibodies would presumably be due to reciprocal immunization, since to date no isoagglutinins have been observed within the Ring dove species nor in the backcross hybrids.

Accordingly, several unions of backcross hybrids, of various ages and in different backcross generations, were made by one of us, (R.T.H.). Kozelka 2 made parabiotic pairs of very young chicks by a metatarsal union. In our experiments a considerably different technique was used. If the birds to be operated on were under a week old, a thorough chilling in an ice box proved an excellent anesthetic, which reduced blood flow to a minimum, and allowed a rapid recovery. In older birds (young adults) sodium amytal, supplemented with ether, was used as an anesthetic. The operative procedure herein described was for the older birds, being nearly the same for young ones.