334 Dr. Dickie on the Marine Algce of the vicinity of Aberdeen. 



the frond in Alaria is covered with scattered pores, from which 

 protrude simple filaments. These pores and simple filaments are 

 evidently the analogues of the basispermal fructification of the 

 Fuci described in a former communication. 



Laminaria digitata, Lamour. — This species occurs in great 

 profusion : in pools at and within high- water mark it is of small 

 size, the plant attaining large dimensions in deep water only. 



In this species I have had numerous opportunities of exami- 

 ning the fructification, which, on this part of the coast at least, 

 is usually found in June and July, at which time that of Alaria 

 is also mature. The specimens of L. digitata which usually bear 

 fruit most copiously are those old distorted individuals found at 

 low-water mark, and which also never attain any great size. It 

 occurs on the lacinise of the frond in the form of elevated spots of 

 an oval or circular form, and more opake than the surrounding 

 parts. Turner had not seen the fructification of this species, but 

 quotes Roth and Stackhouse respecting it, doubting at the same 

 time whether even they had seen the true fructification. The 

 former speaks of it as immersed in the substance of the lacinise, 

 and showing itself by plicae and mucifluous pores ; the latter says 

 it consists of thin inflated pellicles of various forms ; it is added, 

 the papillae perforated at top are often discoverable, particularly 

 after the seeds are shed, even in dry specimens ; further, the seeds 

 are like small blackish dust under a high magnifier (Turner^s 

 'Fuci^. 



On making a perpendicular section of the spots alluded to, the 

 same appearance is presented as in^/«rm, viz.clavate asci arranged 

 perpendicularly toward the surface of the frond, and inclosing 

 simple solitary sporidia ; the latter, however, differ in form from 

 those of Alaria. Figs. 5 and 6 represent the asci and sporidia 

 of the species under discussion. In a former paper it was stated 

 as a reason for believing the acrosperms of the species of Fucus 

 to be one means of propagating these plants, that the fructifica- 

 tion of Alaria and Laminaria is essentially of the same nature, 

 and it evidently is so, the branched filaments accompanying those 

 of Fucus constituting the only difference ; these filaments can 

 scarcely be considered essential parts of the fructification oi Fucus. 

 The acrosperms of Montague, and the reproductive organs of the 

 Laminariea, are therefore evidently composed of asci inclosing 

 solitary simple sporidia. 



It may be observed that some authors include Alaria in the 

 genus Laminaria, as for example Endlicher in his ^ Genera Plan- 

 tarum.' It is very remarkable that L. bulbosa, Lamour., has not 

 hitherto been seen in this vicinity ; I have often searched for it at 

 low tides, but in vain ; and among the thousands of specimens of 

 L. digitata, &c. cast up after storms, not a trace of it has been 



