Darwin was not unaware of his problem, and at various times subscribed to a number of different theories. One popular theory at the time was "blending inheritance" which proposed that offspring were merely an average between the two different characteristics of their parents. But, as Darwin soon realized, blending inheritance (which he called "pangenesis") had its problems. It could not, for example, account for the way in which variations were conserved between generations. If differences between offspring were halved each generation, then the original variation would be rapidly reduced to some average of the starting characteristics. No, that would not work.
Of course, Mendel could have given him the answer. The vital missing link in Darwin's mechanism could be filled using Mendelian genetics. As our story tells, Darwin had just published his book "Origin of Species" as Gregor Mendel was starting to publish the results series of his experiments. These experiments and the analysis of their results were, and are, masterly examples of the scientific method which should have appealed to Darwin's rigorous mind. Mendel's work was eventually published in 1866 in the Proceedings of the Natural Science Society of Bruno, and the clear lesson from this work (whether you understand it or not) was that characteristics do not mix or blend but segregate in the formation of the sex cells, or gametes. Darwin should have immediately grasped the significance of this finding.
Mendel's work and his discoveries, however, remained unknown to Darwin and, indeed, did not become generally known until 1900. Here is the irony. Darwin's library at Down House contains two books. In one is the full text of Mendel's work with all its conclusions. Darwin never read it; the pages are uncut (books in those days came with all the pages joined at the edges, you had to "cut" them open before you could read them). The second book is a collection of abstracts. On each page a current scientific paper is summarized in a single side. Darwin has obviously read and re-read one particular page (his finger prints and annotations are all over it): on the opposite, facing page, is a summary of Mendel's work. The solution to Darwin's biggest problem was right there and he must have stared at it a dozen times, but he never saw it. Even the greatest minds have their blank spots.
Perhaps, as our story suggests, there was a conspiracy to keep Darwin from finding out!!
For Brother Gregory fans (a growing group!), yes, more chapters are planned. In the next one, our hero teaches a class about the new idea that life is made up of cells, uses Mozart as a good example and once more crosses swords with his nemesis Brother Timothy.
Post Scriptum.. There are two schools of thought as to what Mendel knew of, or thought about, evolution. Early in his career Mendel wrote a telling paragraph (some of which is used in our story) in which he concludes that organisms evolved from the simple to the complex. Which would make one think that he would have supported Darwin and his work. The second school of thought suggests that Mendel not only did not understand Darwin but was actually opposed to some of Darwin's ideas.
Contemporary evidence for either school of thought is minimal, and later biographers take one position or another based on slim evidence. I have tried to be fair and suggest that Mendel did not, perhaps, know as much about the subject as some people think, but was open minded enough to accept what he heard. He was, however, curiously reluctant to work with or use any of these ideas.
Mateous Klacel was another story. He enthusiastically embraced Darwin and (as our story tells), America. Some time after the period in which our story is set, Klacel went to America to see for himself what it was like. He also gave spirited lectures defending and explaining Darwinism. But that is another story.