EED SEAWEEDS 87 



in which we can study the reproductive arrangements 

 with some facility. It is common for the tetraspores, 

 the male, and female organs, to grow on separate plants, 

 but all three have been found on one individual. In 

 Fig. 30, a, we see magnified clusters of male organs 

 growing on the thallus of a male plant. These clusters 

 consist of short branches, in each one of which the 

 terminal cell becomes specialized into a male element. 

 The contents of this cell draw away from the cell-wall, 

 round off, and ultimately are discharged through an 

 opening in the form of a spermatium. It is unciliated 

 and passive, so it drifts in the water quite helplessly, 

 and the fulfilment of its fertilizing mission depends upon 

 the direction of the drift. These male elements are 

 produced in goodly numbers, for not only are the 

 branchlets on which they are produced numerous, but 

 after one terminal cell of a branchlet has ripened and 

 been discharged, the next in succession becomes ter- 

 minal, and forms a new male organ within the broken 

 membrane of the old one. 



A small part of a female plant of C. corymbosum 

 bearing a female organ is shown in Fig. 31. This 

 organ is technically designated the " procarpium " 

 (Gr. pro, before; carpos, fruit). In the species under 

 discussion it is generally composed of five cells, and one 

 of these becomes somewhat enlarged, forming a carpo- 

 gonium (Gr. carpos, fruit; gone, generation). This same 

 cell sends out a thin hair, the trichogyne (Gr. trichos, 

 hair; gyne, a female), as per Fig. 31, t. Such an exten- 

 sion of a female cell as the trichogyne is evidently a 

 well-devised arrangement for catching the male elements 

 as they drift. Seeing that these elements cannot swim 



