EUDORINA. 



731 



vegetative cells. In the male coenobia, on the other hand, 16-32 antherozoids arise 

 by the division of each individual cell : these antherozoids are minute elongated bodies 

 with two anterior cilia, their colour being at first green but eventually passing into 

 yellow. The antherozoids M.^ aggregated into a bundle begin to move while still 

 enclosed in the cavity in which they have been produced, and then escape and 

 swarm in the open. On meeting with a female coenobium the cilia on both sides 

 become entangled, and the male coenobium is thus fixed ; it then falls to pieces as 

 in Fig. 412 M^ and M^, whereupon the isolated antherozoids, which now elongate 

 considerably, bore through the gelatinous vesicle of the female coenobium {Sp). Here 



FIG. 413.— i^Kcitr jilatycarpus (after Thiiiet). A the end of a large branch (natural size) ; // fertile branches ; 

 B transverse section of a conceptacle ; d the epidermal tissue surrounding aU; a hairs projecting through the onfice 

 of the conceptacle : b internal hairs ; c oogonia J e antheridia. 



they penetrate as far as the oospheres, and, after groping and creeping around them, 

 apply themselves (often in some numbers) to these. It may be assumed, as has 

 been actually observed in many other cases, that one of these antherozoids bores 

 into each of the oospheres. Here also fertilisation is followed by the development 

 of two membranes, and the transformation of the green colour into a brick red, in 

 which condition the fertilised oosphere then passes through a period of rest. 



Slight though the similarity of the fertilisation last described to that of the 

 Mosses and Vascular Cryptogams may appear to be, there exists nevertheless no 

 real difference as to the main points, since here as there the important fact is the 

 fusion of a small antherozoid with a relatively large resting oosphere ; agreat differ- 

 ence exists only in the fact that in the Mosses ^ndJVa£culaj_Cr^Etogamj^pe^^ 



