In reproduction the algæ are as various as their forms

Here we find the simplest manifestations of sexuality, i.e. the conjugation of similar gametes, but in the evolution of sex the male element alone remains mobile, and in the highest forms the sexual elements are clearly ly distinguishable distinguishab from the complex structures in which they are developed. Vaucheria illustrates a common method of reproduction. The male and female cells originate as short, lateral branches. The male cell, antheridum, gives rise to many biciliated spermatozoids, while the female cell, oogonium, produces an egg-cell, oosphere. A spermatozoid finds its way to this cell and fuses with it (fertilization). A new plant results from the germination of this impregnated body. Among the highest members of the algæ, the Floridiæ, the male elements, spermatia, are motionle and the female apparatus, procarp, is usually much complicated.