270 EMBRYOGENY IN ALG^. 



rangium, and thus fertilisation is effected, and the true spore is formed 

 in the interior. 



In Vaucheria there are thus three reproductive organs : — 



1. Zoospores, which are vegetative or bud-like reproductive organs (moving spores). 



2. Antheridia, with sperm-cells containing fusiform corpuscles, which move hy 



means of two cilia. 



3. Sporangia, with germ-oells, which are fertilised by the ciliated corpuscles- and 



form resting spores, whence the new plants arise. 



Pringsheim has examined the reproduction in two minute Algae, 

 (Edogonium and Bulbochaete. The greater part of the cells of (Edo- 

 gonium contain each a zoospore (fig. 479, 1, a), provided anteriorly 

 with a complete crown of cilia. This body (zoospore) is produced 

 without sexual intercourse ; it germinates and gives rise to a new 

 plant in the same way as a bud does. Between the common cells 

 of the cellular plants occur other utricles, usually more swollen, 

 (fig. 479, 1, 2, b 6), either isolated or in groups. In these are formed 

 motionless spores (or resting spores), which are the female sexual 

 organs. In the individuals which produce these female cells, as well 

 as in others which have no such cells, there occurs a third kind of 

 cell, shorter than the common cell of the plant, and forming often 

 irregular groups. The third kind gives birth to spermatozoids, either 

 at once or after the appearance of an intermediate production of a 

 special nature, which becomes detached from the primordial filament, 

 and contains the male sexual apparatus. In CEdogonium ciliatum, a 

 small species, found attached to the leaves of aquatic mosses, the cells 

 containing the male organs are formed towards the anterior extremity 

 of the filament, between the setiform terminal cells (fig. 479, 1, 2, d) 

 and the upper female organ. In each of these cellules there is formed, 

 at the expense of the contained plastic materials, a single small 

 zoospore called microgonidium (/i,ix^bg, small). This, according to 

 Pringsheim, is the antecedent or generator of the male organs. These 

 male organs have been called androspores (avjjj, male). These andro- 

 spores, furnished with a circle of cilia at their anterior and transparent 

 part, after quitting their mother-cells, move about at first, and then 

 become fixed (in a determinate manner in each species) either to the 

 female organ itself or in its neighbourhood. Pringsheim has seen in 

 (Edogonium ciliatum several androspores fix themselves on the surface 

 of the female organ (fig. 479, 1, 2, c c c). The latter organ continues 

 to be developed, while each androspore becomes a sort of compound 

 cellular plant. In one part of this the spermatozoids are formed, and 

 hence it is called the antheridium. The fixed androspore acts like a 

 mother-ceU. The antheridium, properly so called, represents the 

 secondary utricle produced at the upper part of the androspore, and 

 the stalk of the antheridium is formed by the secondary inferior 

 utricle. The antheridium bears at its summit a small lid, formed 



