60 Rev. M. J. Berkeley on Fucus Labillardierii. 



which the tetraspores are developed are the termination and ex- 

 pansion of those which traverse the axis of the frond, and consti- 

 tute its medullary stratum ; a fact which contradicts in the most 

 formal way the assertion of M. J. Agardh, ' Si denique vera 

 sunt quse de utriusque organi diversitate attulimus, nimirum 

 utraque in eodem individuo nunquam obvenire, evolutionem 

 utriusque esse plane contrariam, alterum vero exterioris strati 

 productum/ &c. (Alg. Medit., p. 62.) On the other hand, it is 

 easy to convince oneself, that from the beginning the compound 

 spore is contained in a linear or slightly clavate filament, and 

 that, though at first simple, it is by insensible degrees only that 

 it is divided into four spores. These at length become free by 

 bursting the common perispore in which they are formed. Would 

 we consider these compou^nd spores as simple spores formed in 

 the endochrome of radiating moniliform filaments, as in the tribe 

 Sph(srococcoidece, I reply, that the assimilation in question not 

 only appears contestable but is absolutely untenable, since the 

 conceptacula of this last-mentioned tribe offer threads radiating 

 from a sort of basilar or axillary placenta; but we have here a 

 disposition exactly the re\ erse. I have indeed found something 

 analogous in a Floridea, of which I have made a genus, under 

 the name oi Nothocjenia. [Vide 'Ann. d. Sc. Nat.,-" Oct. 1843; 

 and plate 10. fig. 3. of the ' Cryptogamic Atlas of the Voyage to 

 the South Pole.'] This Alga presents, like Ctenodus, filaments 

 which converge from all points of the conceptacle towards its 

 centre ; but as these filaments are articulate and moniliform, the 

 spores contained in each endochrome, of which they are a trans- 

 formation, are simple and not compound spores ; in other words, 

 they are not tetraspores. 



" We have then a Floridea, containing, — not in a single cavity 

 but in a plurilocular receptacle, which I call pohjthecium, for 

 each of these cavities is as it were an introverted Namathecium, — 

 compound spores accompanied by paraphyses, as the simple spores 

 of Fucacea, or the compound spores or asci of Lichens and of 

 various Fungi, which are isolated at maturity and fall into the 

 middle of the cavity. This curious Floridea shows us then — 1st, 

 The profoimd analogy and, as it were, confluence of two kinds of 

 reproductive bodies. 2nd, Their common origin (at least in the 

 present Alga, contrary to the assertion of J. Agardh). 3rd, A 

 second example in Floridece of the convergent direction of the 

 sporigerous filaments, — a direction hitherto supposed to be pecu- 

 liar to Fucaceae. 



" These are the most important observations I have recorded, 

 and you will at once see what bearing they have on the division 

 into Aplospores and Chorispores. I do not recognise a specific 

 difference in the two Algse -which Mr. Harvey has so kindly com- 



