Comparative table of averages of area and yield of the wheat crop in Manitoba, Canada from 1883-1904.

Photograph of a man standing next to a field of barley wheat in the early/mid 20th century.

Photographs of the development of four wheat seedlings in aqueous extracts of soil samples from poor Cecil clay, from good Cecil clay, from poor Leonardtown loam, and from good Leonardtown loam.

Photograph of four samples of the development of wheat seedlings in aqueous soil with two from Takoma Park, Washington DC and two from Statesville, North Carolina in the mid 20th century.

Photograph of five samples of wheat showing the effect of cinnamic acid found in certain plants and related to cumarin.

Photograph of samples of wheat showing the effects of esculin, which is closely related to cumarin and found in various plants.

Photograph of five samples of wheat showing the effect of quinone found to result from the action of a soil fungus on proteids.

Photograph of eight samples of wheat showing the effect of vanillic acid.

Photograph of six samples of wheat to show the effect of vanillin, found in vanilla beans, lupines, beets, roots, oats, and decayed wood.

Located in I.A.P.G.R-E.R.S. Staff Papers 1991. Part 2.