Inheritance of chromosome number in pigs.

(Received 23rd January 1968, revised 25th May 1968) Summary. All possible crosses were made between European wild pigs with either 36 or 37 chromosomes and domestic swine with 38. The 36 \m=x\36 cross produced only pigs with 36; the 36 \m=x\37 and 37 \m=x\38 crosses yielded the parent numbers in about equal numbers of pigs. All pigs resulting from the 36\m=x\38cross had 37, while crossing 37\m=x\37gave progeny with 36, 37 or 38 in about a 1:2:1 ratio. It is surmised that the three unpaired members in the 37-chromosome animal act as a trivalent during meiosis with two telocentric chromosomes behaving as a unit. No firm evidence indicated reduced fertility in any of the animals nor