Chapter the Second
Visitors

Letters for Elements


Upstairs in Mendel's room, the monks had just finished explaining the nature of the hybrid experiments to the two Englishmen.
"Hybrids, then, are of a composite nature," said Brown. "If a plant with a dominant character, such as round seeds, is mated with a plant having the recessive character, such as angular seeds, then the hybrid always shows the dominant trait, never the recessive trait?"
Mendel nodded.
"And there is never any mixing or blending of these traits?"
"Not in our work with Pisum," Brother Joseph told them and pointed to some of Mendel's notes. On the page were a series of letters in various permutations and combinations.

"If we let the letter A represent the dominant trait and the letter a represent the recessive trait then, "A" and "a" are the parental forms, and "Aa" is the hybrid produced by mating the two. It shows the dominant form, round seeds, in this case."
"But you know that because of what happens next," shouted an excited Sam Giddings. "When the "Aa" hybrid is allowed to self fertilize, the next generation show a mixture of dominant and recessive forms in the ratio 3 is to 1."
"The re-emergence of the vanished recessive form shows that it was present as an element in the hybrid, but could not be expressed until it once again arrived in its pure form in the following generation." Brown was slowly becoming as excited as his more volatile companion.

"Hooker and Darwin will definitely be interested in these results," Giddings told the group, "your work makes clear how variation in form can be inherited from one generation to the next."
"An element that controls the characters in form is passed from one generation to the next," said Brother Matthew.
"But this element influences the form only when in either the dominant condition in a hybrid, or when it is the sole element present in the recessive form, " added Brother Joseph, making sure their guests understood the significance of their work.
"And how do you explain the transmission of this element from one generation to the next?" asked Brown.
"Ahh," said Mendel.

"I have given this matter some thought. We must assume that the reproductive cells are all alike and agree with the foundation-cell of the hybrid." He looked at the group and went on, choosing his words carefully. "In the opinion of renowned physiologists, for the purpose of propagation one pollen cell and one egg cells unite in Phanerogams into a single cell, which is capable by assimilation and formation of new cells to become an independent organism." This was background information, but he could not be sure how much of this his guests understood. The exact details of reproductive cell formation and of fertilization were still new and 'hot' topics of scientific discussion. Mendel's ideas were cutting edge science.