_Separation or Scission._--The individual dissevers into two parts, and each of these, made independent, reproduces the generator. This is the most simple form of genesis, in which the function of reproduction is not distinct from the other functions, but merges into them. _Endogenesis._--Within an individual many other individuals are formed; the parent opens, and, destroying its own individuality, dissolves in its offspring. _The individual by itself alone generates other individuals._--The parent generates through special organs and without dissolving in its offspring. The individuals generated and separated from the generator are eggs, seeds, perfect organisms; but in every case these are always elements evolved within the generator through special organs. The generative function is already marked and distinct in a laboratory which detaches and prepares some of the elements of the individual, so that they may reproduce it. _Monoecious Sexual Generation._--A step higher, the generative laboratory becomes complicated and divides into two parts, one of which brings forth the egg, the other the fecundating element. Each, for its own account, prepares the element destined for the reproduction of the individual; but if both do not come in contact, the new being is not generated. We have the sexes quite distinct, but enclosed within a single individual. Strange to observe, however, we behold an individual that generates an egg which cannot be fecundated by that individual's seed; or an individual that produces a seed which cannot be of any service to the egg. A duplex embrace of two hermaphrodites which interlace a quadruple love, and the appearance of winds, insects, or birds, as fecundatory paranymphs, resolves these problems of a most singular generation. _Dioecious Sexual Generation._--Finally, the generating organs, too, separate and fix themselves each upon a single individual, which is sterile in itself, produces but one of the generating elements, and, therefore, must combine with the other; and by such union they may produce the new creature: the sum of two individualities, the male and the female, the father and the mother. Man loves in twain; but although, like the other superior animals akin to him, he presents a dioecious sexual generation, yet in his inmost tissues he also possesses the _endogenous_ genesis and the genesis by _scission_, and presents in this regard the remains also of the elementary forms of life enclosed within him.