Okay this is a rather strange tidbit but in Dr. Chase's Recipes ©1866 I found this tidbit:
The Sex Op Eggs.—Mr. Genin lately addressed the Academy des Sciences, France, on the subject of the sex of eggs. He affirms that he is now able, after having studied the subject for upwards of three years, to state with assurance that the eggs containing the germ of males, have wrinkles on their smaller ends, while female eggs are emooth at the extremities.
While on the subject of eggs, you will excuse me for putting in a couple of items more which appropriately belong to other departments:
The above tidbit had me searching for more information on this during the 19th Century. I came up with this next tidbit from "The Book of the Farm" ©1890:
Sex of Eggs.—It has been said that the position of the cell that contains the air in an egg determines the sex of the chick — if the cell occupies the exact apex of the end, which is always the large end, the chick will be a male; and if on one side of the apex, it will be a female. But this cannot be accepted as being reliable, nor can any of the other numerous supposed methods for predetermining the sex of eggs.
Hens are required to lay eggs for the dealers of eggs, and young cocks are required for the dealers of fowls, and for converting into capons. Both businesses are carried on by different persons, and .hence the utility of determining the sex of eggs. M. G6nin says, that as the female skeleton of a fowl contains smooth bone, and that of the male rough, so the male egg is wrinkled at the small end, and the female is smooth at both ends. This is the result after three years' experience.
But all the indulged notions as to determining the sex of eggs, and regulating sex in breeding, have, in the case of poultry as of other animals, been proved over and over again to be fallacious. We take it that this is a law wisely kept beyond the knowledge and control of man.
The matter of sex of the egg is of no importance on a farm, as good chickens of both sexes are valuable as an article of food.
I point out these two tidbits as a reason to search further, know your time period, know what was proven to be a fallacy or just an oddity. Then have fun with it.