6. Collection of indigeneous corn.
The studies on authentic indigeneous corn are being continued and I hope to publish soon the first results, together with Dr. Cutler. There seems now to be little doubt that one may classify to some extent native corn in accordance with the grouping of the Indian tribes. The main bulk of our collection has been furnished by tribes of the Tupi-Guarany group. There is comparatively little difference between the types cultivated by the Emeremhon (north of the smouth of the Amazon), the Cayabi and other tribes (North Mato‑Grosso, almost in the middle of Brazil), the Paragayans and the Chiriguanos (Northern Argentina). The predominant types are: Soft large‑grained yellow (aleurone color); semi‑hard white; orange, variegated or red pericarp with some tendency towards dent. There are two rather primitive types; the large ears vith flexible rachis and half‑submerged grains from northern Mato‑Grosso (Caiabi and Bororo Indians) and the small grained pointed pop corns of the Tupi Indians, which contain many "Tripsacoid" characters.
Both the corn cultivated by the Chavantes of Central Brazil and numerous types cultivated by the Cainguang of Parana in the South are completely different, without the predominance of yellow and orange types.
No explanation has as yet been found with regards to the hard orange flints called in the Argentine and Urugaya "Colorado" and "Quarantino", and in S‹o Paulo "Cateto". It may be extracted from crosses of soft yellow and pointed pop.
The genetical analysis of the material is being continued. In the color of red or purple (Pr/pr) aleurone as contrasted to colorless, at least three factors are involved, one the dominant inhibitor Ci. There is at least one dominant inhibitor of yellow endosperm in pointed pop. Floury has more often a polyfactorial basis, rather than the simple fl gene. Waxy seems rather common. Nothing as yet can be stated with certainty about the large number of plant, cob and glume colors. Rose or wood‑colored husks are due to new alleles of the P‑series.
The Mendelian ratios in Paraguay corn are all perfectly normal. In Bororo corn a gametophyte factor in the IX chromosome causes a deficiency or excess of recessives.