'2\s mi: .luiuNAi. ok botawi 



In all cases the full type of sexual mechanism alone demands 

 special consideration, as representing theoretical conceptions of 

 syngamy, and hence the primitive aspect of the life-cycle. Drawings 

 of the early stages of the formation of ascogenous hyphae (Baur, 

 Nienburg), as available, are not readily distinguishable from figures 

 of the phenomena seen in the development of the carposporophytes 

 of the more generalized Floridese (Chondrus, Gigartina). The 

 mechanism remains distinctly algal, aquatic, and essentially marine 

 in inception. That eveiy condition and possibility of deterioration 

 in the original cytological mechanism should obtain, or even be 

 general, goes without sajnng, as the chances of maintaining aquatic 

 (plankton) gamete-fusions become the more difficult or hopeless 

 under subaerial conditions. Again, this follows as a matter of course, 

 immediately it is recognised that these plants are, at best, only the 

 most depauperated and residual of algal types, and by no means up-grade 

 products of syntheses, in which sexual mechanisms are being con- 

 stituted de novo to suit the conditions of the land. Hence examples, 

 however abundant, of apogamy, parthenogamy, or in the limit, 

 pseudogamy, though complicating the story of individual genera, 

 acquire very subsidiary importance l ; as again does the general 

 elaboration of communal sporophytes, where the developing asexual 

 ramuli of adjacent sexual carpogonia become interw r oven to a con- 

 fluent hymenium, or the zygote itself is communal and coenocytic. 

 None of these phenomena would excite much surprise in the case of 

 modern Florideaj of the sea, any more than does the complete loss of 

 sexual mechanism in certain forms (Rhodochorton and many Chan- 

 transias), or the suppression of the tetrasporangial stage in others 

 (Nemalion, Scinaia)^. The same applies to the Laboulbeniaceae, 

 and a neat example is given by Faull, in which pseudogamy follows 

 by the \itilization of a migrant daughter nucleus of the trichophorie 

 cell 3 . Similarly after demonstration of the remarkable phenomena 

 of the possibilities of nuclear migration in the post-sexual phases of 

 ' auxiliary cell ' mechanism, similar nuclear migration in Lichen- 

 carpogonia, not only become inherently probable, but the case of 

 presexual nuclear translation, rendered possible by the retention of 

 'primary pits,' in achieving the act of syngamy (undoubtedly effective 

 at some time in the case of the Laboulbeniaceae 4 , even if not directly 

 observed in living forms) may be accepted as equally probable in the 

 filamentous carpogonial ramuli of Lichens ; again with equally a 

 very secondary application to the original theme. In absence of a 

 more definite key to the origin of these groups, the expression of 

 reproductive abnormalities has attained undue prominence ; their only 



1 However exciting to the cytologist ; i. e. nucfear phenomena as inherited 

 from the cell-soma of the plankton-phase, require to be wholly dissociated from 

 the structural morphology, in terms of larger aggregates in tissues and members 

 of the benthic phase. 



2 Cleland (1919) Ann. Bot. xxxiii. p. 343 (1919). 



3 Faull (1911) p. 652, suggestive of the mechanism of initiating phenomena 

 of pneudogamy. 



4 That no true sexual fusions have been so far observed is phyletieally 

 immaterial. 



