Complex sentence: The ovaries, which are of large size, are prepared for caviar, for this purpose they are beaten with switches, and then pressed through sieves, leaving the membranous and fibrous tissues in the sieve, whilst the eggs are collected in a tub.
Split into simpler sentences: The ovaries, which are of large size, are prepared for caviar. They are beaten with switches, and then pressed through sieves, leaving the membranous and fibrous tissues in the sieve, whilst the eggs are collected in a tub.