Mendel, Corn and his Seed Dealer
Beyond Peas and the laws of gravity
Beyond Peas and the laws of gravity
One of the things I enjoy the most in science is the serendipitous nature of discoveries. I decided a while back, as part of venturing into the agriculture field, to not only read some fantastic books¹ but also check some of the historical sources and try to find some unknown connections. Mainly with my obsession from my physics days, the 1904's Louisana Purchase Exposition, due to Boltzmann and Poincare's presence during the Academic Congress. I was surprisingly happy to see Hugo De Vries, indeed, give a talk at the congress concerning² (emphasis wholly mine):
series of researches, experimental and theoretical, touching problems in physical chemistry and plant physiology, in the theory of heredity, and especially in the new experimental science of evolution. In the last named field De [V]ries has accomplished results which will make an epoch, at once demonstrating the fundamental thesis of Darwin, and supplementing the principles of Darwinism.
For De Vries has been able to see with his own eves the actual evolution of several new plant forms possessing the characters of true species, and has accumulated a vast amount of exact evidence, in support of the theory that new species arise suddenly from marked variations of the discontinuous sort, called ‘mutations’ rather than by the gradual accumulation, through successive generations, of slight differences due to the ordinary ‘fluctuating variation,’ as Darwin had supposed.
De Vries is famous for, among others, independently re-discovering the principles that Mendel found almost a half-century before. A fact almost overlooked if it wasn't mainly due to the publication of Mendel's letters to Nageli.
During 1856–1863, Mendel performed some experiments with peas, i.e., Pisum, that laid the foundation for our understanding of genetics. However, his discovery was forgotten for almost 40 years.
After presenting it and subsequently publishing a paper at the Proceedings of the Natural History Society of Brünn in 1866, Mendel corresponded with Swiss Biologist Karl Nageli regarding his experiment, at the time one of the leading biologists in Europe, starting on 31 December 1866³! Talk about a new year's resolution. His letters are easy to find online and were surprisingly approachable.
The English translation of his letters can be found here.
After one unresponded letter, Mendel sent a second letter around mid-April 1867; ghosting someone was ambiguous back then when there were thousands of ways letters could get lost. He included even more information in this second letter than in the first. In particular, my favorite quote so far is due to the area I currently work in.
I have obtained luxuriant plants of Linaria vulgaris+L. purpurea; I hope they will flower in the first year. The same may be said of Calceolaria salicifolia and C. rugosa. Hybrids of Zea Mays major (with dark red seeds)+Z. Mays minor (with yellow seeds) and of Zea Mays major (with dark red seeds)+Zea Cuzko (with white seeds) will develop during the summer. Whether Zea Cuzko is a true species or not I do not dare to state. I obtained it with this designation from a seed dealer. — Mendel April 1867
A corn seed dealer! (Zea Mays, being the scientific name for corn) Much like automobiles, agriculture in the United States is dominated by dealers who develop personal relationships with growers and their operations. A profession that is much older than I believed. By 1869 he had finished those experiments and only referred to them in his 8th letter on 3 July 1870.
Of the experiments of previous years, those dealing with Matthiola annua. and glabra, Zea, and Mirabilis were concluded last year. Their hybrids behave exactly like those of Pisum. — Mendel July 1870
So while corn genetics is known to be rather complex. He was able to get similar results to peas. And according to Marcus M. Rhoades⁴ since:
The development of aleurone color depends upon the complementary interaction of the dominant alleles of four different loci and Mendel could have encountered F2 ratios of kernels with colored to colorless aleurones such as 3:1, 9:7, 27:37, depending upon how many of the aleurone genes were heterozygous.
And explicitly defines him as "undeniably … the first maize geneticist"
Furthermore, the letters also give a glimpse into Mendel's personality and sense of humor. His first official reply to Nageli starts with a proper self-deprecating joke about gravity!
My project of studying the Hieracia of this locality in their natural environment has, unfortunately, been carried out to only a very limited extent. Lack of time is chiefly to blame for this, and I am no longer very fit for botanical field trips, for heaven has blessed me with an excess of avoirdupois, which becomes very noticeable during long travels afoot, and, as a consequence of the law of general gravitation, especially when climbing mountains.
[1] Catherine Zabinski, "Amber Waves," The University of Chicago Press, 2020
[2] Wm. Harper Davis, The International Congress of Arts and Science, Popular Science Monthly, Volume 66, Nov 1904.
[3] http://www.esp.org/foundations/genetics/classical/holdings/m/gm-let.pdf
[4] M.M. Rhodes, "The Early Years Of Maize Genetics," Ann. Rev. Genet. 1984. 18:1-29.