The Royal Society read the latter part of Letter L-157 about sperm and eggs in sheep and rabbits

June 27, 1685

At their meeting on 25 July/4 August 1683  (O.S./N.S.), the Royal Society had also asked Leeuwenhoek to examine the eggs of a silkworm.


Birch, History, vol IV, p. 407, 17 June 1685 O.S. in London, 27 June 1685 N.S. in Delft:

The latter part of Mr. LEEWENHOECK's letter of March 30, was read, concerning the manner how he conceived the animals in seed to cast their first skin, having a long tail, and to be nourished by the egg; the description of the foetus of a sheep after seventeen days; of the eggs in the ovarium, two of which were red and as big as a pea, when the whole foetus was no bigger than an eighth of a pea: of the description of the animal in the seed of a rabbet: of the uterus of a rabbet two days after it had been with the buck; of another uterus after six days; of the foetus of a sheep three days old.

The secretary was ordered to return thanks to Mr. LEEWENHOECK for this curious letter, and sir JOHN HOSKYNs proposed to desire him, that he would examine, with hIs microscope, the eggs of silk worms, that have been impregnated, and those, that have not; it being probable, that those eggs are fit for making a farther discovery; they being likewise not difficult to procure.