and Propagation of marine Plants. 1 57 



which is entirely deftitutc both of the veficlcs and the external fila- 

 ments, and yet produces its feeds in a manner exactly fimilar to that 



before defcribed ? In.ih .rt, as the means by which Nature con- 



du6ls her oi^)erations are always appropriate to her ends, we may 

 conclude, that if the fine vefTels or fibres in the veficles had any im- 

 mediate reference to a ftate of florefcence, they would either be ex- 

 tended throughout the internal fubftance of the frond, to carry on 

 their fecrct and fubtile operation ; or would be furnillied with fome 

 cNternal apparatus, which might give colour and fupport to the 

 hypothefis. 



A particular defcription of the air-bladders, or veficles, which 

 Form a curious part in the ftru6ture of feveral of the Fuci, \sill clofe 

 thefe remarks. It might naturally occur to any cafual obferver, 

 that the veficles alluded to could not be formed, if they had not 

 fome means of collecting and retaining a greater portion of air than 

 that which may exift in an equal given fpace of the folid frond. 

 Nature therefore feems to have furnillied them with numerous tra- 

 cheas or air-veffels, furpafllng in tenuity the fineft hair. Thefe are 

 a combination of fibres inofculatcd together, which proceed from the 

 cellular fubftance, and freely exert their elaftic influence from the 

 interior furface of the cavity. They may be found in all the inflated 

 Fuci; and as they are very fimilar in their appearance, fo, probably, 

 they may be in their cecongmy, to that fine woolly fubftance which 

 is found at the broken ends of fome leaves, and which the learned 

 Grew has pronounced to be a (kein of air-veflels. Thefe capillary 

 vefTels in the bladders of the Fucus probably contribute their aid to 

 dilate and extend that part of the frond into its oval and veficular 

 form ; and bring part of that elaftic fluid into aftion, which is well 

 known to exift in all plants without exception. Since this paper 

 was written a remark has made its appearance, in a very valuable 



work 



