The following chromosome map shows the loci of those interchanges for which there is cytological information. It is based on data presented in previous Coop Letters, whatever has been published and in addition unpublished data of Dr. C. R. Burnham. The scheme Anderson has used is followed, the breakage points being measured from the spindle fiber insertion region in tenths of the length of the particular arm in which the break occurred. Interchanges for which only genetic information is available are not listed.

As is customary, the map presents the cytological lengths of the chromosome which are in proportion, using chromosome 10 as 100 units. The length of each arm is given at the spindle fiber attachment region, the total chromosome length being the total of the two arm lengths. The long arm/short arm ratio is given at the bottom of the map.

The following example illustrates the use of the map: translocation 1-2a is listed as 2a on chromosome 1 opposite .7 on the long arm; on chromosome 2 it is listed as 1a opposite the locus .6 on the long arm. When more than one break has occurred at the same point, they are grouped together. For example, there are 5 translocations at locus .3 on the long arm of chromosome 2. Breaks which have occurred in the satellite of chromosome 6 are grouped in that region but their position in the satellite arm is not definitely known. 6-9a occurred in the nucleolus-organizer region. 2-6a and 5-9a involved the short arm of chromosome 6, but their relation to the spindle fiber insertion region is not known, hence they are given 0+ ratings.

On completing this map Dr. C. R. Burnham has given advice and suggestions and a final check on the figures.


Anderson, Maize Coop Letter, March 5, 1940
____________, " , April 15, 1939
____________, " , March 6, 1938
____________, " , March 4, 1936
____________, " , March 6, 1935
____________, Genetics 23: 307-, 1938
____________, " 24: 385-, 1939
____________ and Brink, Genetics 25: 299-, 1940
Clarke and Anderson, 1934
Emerson, Maize Coop Letter, March 5, 1940
____________, March 23, 1937
Burnham and Cartledge, Journ, Amer. Soc. Agron. 31: 924-, 1939

Edward Garber