OF ARTS AND SCIENCES. 



189 



on the upper part are more numerous and more conspicuous than at 

 any other stage. They are larger in these fronds than at any time 

 previous, as will be noted below. In the basal third or half of the 

 blade, however, the cryptostomata are entirely wanting. The color 

 of this portion is darker, and it is thicker and more leather}'. 



The stipe is more flattened at the top, and the holdfast is larger and 

 firmer. Occasionally one is found in which one or more of the hap- 

 teres is branched. The branching, however, is only a simple forking 

 of the haptere, and may perhaps be regarded as indicating two hap- 

 teres, fused together above but free below. This brandling, as far 

 as my experience goes, is decidedly rare. 



At about this period, and in some cases also somewhat earlier, 

 the blade splits vertically into two or more divisions. Two segments 

 seems to be the rule in the narrower blades, but in the wider ones there 

 are generally three. I have seen a number of specimens where there 

 were four, and in the herbarium, of Mr. Collins I have examined one 

 in which there were five. The splits are continued almost to the very 

 base of the frond, and the segments are more or less strap-shaped. 

 The old fronds split very readily in this vertical direction, and one 

 often finds them cast ashore in the springtime split down to the hold- 

 fast itself. In Mr. Collins's herbarium there is a specimen which had 

 been split down thus ftir when young, and each half had proceeded to 

 continue growing, and there are two more or less perfect plants in that 

 case from the same holdfast. It reminds one of the famous bifurcate 

 specimens of Laminaria digitata, of which a summary is given by 

 Le Jolis.* 



2. Adult. — As the season progresses, the plant ceases to grow so 

 actively as at first, and the tip wears away faster than it is renewed. 

 Consequently, the plant becomes shorter as the summer advances, but 

 it also grows thicker and denser. I have unfortunately no specimens 

 collected early in July, but through the kindness of Dr. G. H. Parker 

 of Harvard University I have some excellent specimens collected late 

 in July. These are shorter than the earlier specimens, are of a dark 

 brown color, and very leathery. They show no traces of ciypto- 

 stomata. In Se[)tember I collected very similar specimens at Nahant 

 with zoosporangia just forming. In October, specimens with well 

 formed zoosporangia were not uncommon at the same place. Fruit- 

 ing specimens of this species may be found from October on until 

 May of the next year. 



* Examen I., p. 540. 



