Laing. — Observations on the Fucoideae. 305 



Observations. 



1. Ectocarpus siliculosus. 



In Hooker's description of this there is an evident misprint, 

 the length being put down as T ^ inch instead of 12 inches. 

 I have at present no remarks to offer on — 



2. Sphacelaria paniculata. 



3. ,, funicularis. 



4. Asperococcus sinuosus. 



5. Zonaria velutina ; and 



6. Desmarestia ligulata. 



7. Adenocystis lessonii. 



Hooker's description is: " Eoot, a small disk or shield. Frond 

 a dull green or olive-brown, membranous, pyriform sac, on a 

 slender short stalk, hollow or full of water, coated with a thin 

 layer of vertical clavate articulate filaments. Spores pedicelled, 

 pyriform, attached to the base of the filaments and scattered 

 over the whole frond." 



Fig. 1 shows a transverse section through the bladder- wall, 

 which consists of two tissues, a narrow epidermal layer of small 

 coloured cells, and an inner layer of oblong colourless cells. 

 From the latter spring long jointed hairs, covering the interior 

 of the bladder and giving it a slightly downy appearance. They 

 are generally colourless, but sometimes contain colouring matter 

 aggregated into more or less rounded masses. 



The reproductive organs of this little plant are very interest- 

 ing, because it seems to possess two kinds of zoogonidia. Thuret 

 (" Ann. de Sc. Nat. Bot.," 1850, p. 235) has described the same 

 occurrence in various other genera of the ~Phaospore<E. Harvey, 

 (" Phycologica Australica," PI. xlviii.) says that, in addition 

 to the ordinary fructification on the surface of the bladder, " the 

 frond of Adenocystis is dotted with hemispherical gland-like spots, 

 from which lyssoid filaments issue, and which may be possibly 

 connected with antheridia." I have made a large number of 

 sections of these conceptacles (the gland-like spots of Harvey,) 

 without obtaining any very definite results. Fig. 2 shows the 

 most successful of these sections. In it appear two large cells, 

 (Fig. 2, a. and b.) which perhaps contain zoogonidia. I was not, 

 however, able to determine the position of attachment of these 

 cells. 



The conceptacles appear in very young specimens, and con- 

 sequently I have not been able to ascertain anything about their 

 mode of development ; but, judging from the fact that the 

 epidermal tissue passes round the whole conceptacle, it would 

 appear to be the result of invagination alone. Thus it would not 

 be altogether homologous to the conceptacle of the Fucacece, which, 



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