INTEODUCTION TO CETPTOGAMIC BOTAIJT. 191 



from the base, as represented in my figure, or from some other 

 portion of the walls, though the spores radiate from the centre 

 of the nucleus, and the cells in the incrassated portion of the 

 placenta are distinctly though irregularly moniliform. The 

 only resemblance is in the cuneiform spores, which have 

 already been seen in Chylocladia (Fig. 44, b). 



9. ChjETANgie^, Kiitz. 



Frond cartilaginous ; conceptacles immersed in the medullary 

 substance, producing articulated threads from every part of 

 their walls which converge to the centre, the terminal joint of 

 each branchlet producing a spore. 



167. The curious Algee in this division are peculiar to the 

 southern hemisphere. Species occur at the Cape, the Auck- 

 land group, the Falkland Isles, Chili, and New Zealand, and, 

 if Porphyroglossum is allied, in Java. They are characterised 

 by the confluence of the placenta with the cavity of the con- 

 ceptacle, every part of which gives rise to articulated threads 

 scattered or in fascicles converging towards the centre, and 

 bearing at the tip of each branchlet a single spore, which has 

 a single envelope. I have already pointed out, in the last 

 division, that the placenta is not always basal ; and, supposing 

 the fertile points to be multiphed, we have the structure just 

 mentioned, which is in fact nearly that of the fruit of Fuca- 

 cece. Dr. Harvey remarks* that it is possible that they may 

 eventually prove to have a close relationship with Pterocladia. 

 I have figured the placentation in Oelidium (Fig. 47, c), and 

 the portion of the axis which bears the spore threads, or in 

 other words the placenta, instead of passing through the 

 centre of the cavity, is confined to one side only, we shall have 

 the lateral placentation of Pterocladia. I am myself rather 

 inclined to compare the conceptacles with those of Polyides, 

 where the development of the spore-threads from the axis is 

 confused, whether the cavities in which they are produced be 

 considered nuclei or nucleoli. Dr. Kiitzing was the first to 



* Nereis Bor. Am. part ii., p. 114. 1 am sorry that the fruit in my 

 own specimens is in a very early stage. The extremely delicate threads 

 of which the medullary substance is composed, giving rise to monili- 

 form threads on the surface, are very peculiar. 



