1892.] Phenomena, and Development of Fecundation. 293 



cleus (figs. 22 and 23). Shortly after fertilization a partition 

 forms between the trichogyne and the egg cell, debarring the 

 entrance of further sperma I ia and a Hording thus an excellent 

 illustration of what Whitman has termed Self-regulating 

 receptivity." After fertilization the egg cell does not separate 

 from its previous tissue connections, as in the oogonia of other 

 green alga?, and the archegonia of the archegoniata, bnt 

 remains in continuous connection with the hypogynal cells 

 through which it is nourished. 



In the simplest case {HvlwinthodwIU-u) the ovacell develops 

 from its surface many several-celled lilaments, t>of>l<istnntix, as 

 they are called, which form usually a closely compressed tuft, 

 A single carpospore is developed at the apex of each of these 

 ooblastema filaments {Nemalion, etc.) In this case, it will be 

 noticed, all the ooblastema filaments are nourished through 

 the egg cell. 



In the Gelidese, a slightly higher form, the fertilized ova 

 from its surface cell develops a single filament, termed the 

 ooblastema, which turns toward the axis of the blanch 

 and, ramifying abundantly, winds around this, sending 

 branches into the highly nutritive outer layer of cells of the 

 hranch and connecting with some of these cells by the devel- 

 opment of pits. Being thus abundantly nourished through 

 this tissue, the branches of the ooblastema filament develop 

 from each of the clavate erect terminal branch cells, either a 

 single spore or short chains of two or more. In this case it is 

 seen the ooblastema filament become- in a sense parasitic upon 

 the tissue of the parent plant. 



In the families Crytmemiese and Squatuaricn a single or at 

 least few ooblastema filaments develop from the fertilized egg 

 cell. These creep about until they come in contact with 

 certain specialized cells of the branch known as auxiliary cells. 

 with which they enter into connection directly or by the 

 development of conjugation processes. In many cases the 

 union thus formed is limited to a fusion of the protoplasm 

 while the cell nuclei remain separate, (Dudremaya). In this 

 case a process issues laterally from that half of the conjugation 



