This is a high quality book of the original classic edition. This is a freshly published edition of this culturally important work, which is now, at last, again available to you. Enjoy this classic work. This paragraphs gives you a quick look inside: The cells of these organs, called sexual glands, have the power of reproducing themselves so that they reconstruct the whole individual (the type of the species) from which they arose, in an almost identical form, by conjugation (sometimes also,