HISTORICAL REVIEW OF THE FLORIDE^ 33:^ 



on which the curved carpogonial ramulus is refiexed in orientating it 

 to point the trichogyne to the exterior), as draining the food-supply 

 of the f)arent by taking possession of the cytoplasm of a weaker 

 vegetative cell in the path of conduction, and replacing the original 

 nucleus by an active one sexually produced i. This again is rendered 

 possible by the mechanism of secondary pit-connection, dependent in 

 turn on the peculiarly soft penetrable wall-membranes. It is the 

 blind adhesion to conce^jtions of ' impenetrable,' ' rigid,' cellulose 

 envelopes, based on the stud}'- of the xeroj^hytic land-tlora, that has 

 hindered perception in dealing with the simpler polysaccharide mem- 

 branes of early marine phytobenthon ; and more than any other 

 group the Floridea? present the negation of older misconceived and 

 traditional cell-theory. 



Probably the clearest view to be taken of the Floridese, as they 

 exist at the present time, is that of a multitude of, so far as they can 

 be traced, quite distinct phyla ~, as the survivors of a specialized and 

 narrowly circumscribed race of Marine Algse, the origin of which is 

 beyond recall ; all the living representatives (300 genera) are on a 

 closel}" comparable physiological plane, and are alike in the attainment 

 of an advanced limiting phase of reproductive mechanism, with a 

 practically constant limiting type of antheridium, oogonium, and 

 unilocular sporangium (as tetra sporangium) : all present the same 

 secondary supersession of flagellated heterogamy, with consequent 

 attached, parasitic, and hence vegetatively decadent carposporophyte, 

 the more so as the latter is immersed in the parental tissues. On the 

 other hand, the phyla diverge widely (1) in respect of types of 

 somatic construction and organization, in correlation with factors 

 of mechanical tenacity, the relative amount of surface-exposure for 

 absorption from the nutrient medium, and utilization of the available 

 light-supply, according to their habitat in the different biological 

 stations of the sea ; but all tending to more quiet water, and taking 

 the chances of depth and diminished light in order to secure it : 

 also (2) with regard to their internal economy, becoming more 

 specialized in relation to the new stimulus of the parasitic carposporo- 

 phyte, which is a drain on the system — and requires to be nourished 

 and 'protected as it becomes less and less able to continue as a 

 mechanically efficient, autotrophic, individual. Ultimately the latter 

 reduces to the status of a mere reproductive organ (of sporangium- 

 habit j, and a mechanism for the emission of the free carpospores may 

 be added to the parental tissues. 



It is obvious that the phases of haustorial connection, progressively 

 more intimate and devastating in their relation to the parental thallus 

 they drain, constitute but one aspect of the question. The production 



' Oltmanns (1898), Bot, Zeit. p, 114, for Callithamnion and Dtvdresnaya 

 purpyj-ifera ; Algae (1904), pp. 689-700. 



■^ For example, the Nemalionales of Schmitz, as including all types with no 

 specially fore-shadowed auxiliary cell, or with none at all, are merely a non- 

 descript collection of vestigial lines, which in somatic organization have no 

 connection whatever with each other, and the brilliant generalization which 

 groups them by the physiological factor of zygote-nutrition, merely expresses 

 convergence in this particular respect : cf. Nemalion, Batrachospermum, Chan- 

 trun.^ia, Lemanea, Thorea, Scinaia. Dermonema. Galavnura, etc. 



