180 PROCEEDINGS OF THE AMERICAN ACADEMY 



the same locality, even after a very careful search. lu June, 1888, 

 only a very few plants were to be found in the tide-pools at Nahant, 

 and those occurring in the very lowest; but in May and June, 1889, 

 all the tide-pools were full of young plants, even the very upper- 

 most. In the mass of kelps thrown ashore after storms are to be 

 found comparatively few individuals of this species. They are usually 

 more abundantly cast up in February and March than in the other 

 months, and are for the most part old plants, which are often much 

 mutilated. 



Material. — The material on which the present paper is based was 

 collected, for the greater part, by the writer on the shores of Maine 

 and Massachusetts. During the year 1889 the tide-pools at Nahant, 

 Mass., furnished an excellent place for observing this species in almost 

 all of its stages. The first collections were made in the last week of 

 April, and the locality was visited from time to time imtil June of the 

 following year. Collections were also made at various times at Marble- 

 head, Mass., and at Peak's Island, near Portland, Maine. From these 

 various collections specimens of all ages were preserved in alcohol of 

 about fifty per cent strength, and numerous notes and observations 

 made from them while living. Consequently a number of interesting 

 facts concerning the development have been revealed, and certain rela- 

 tionships more firmly established. In the following paper the mor- 

 phology of the different periods in the life-history will be given first, 

 and then the histological details of these same periods. 



Morphology. 



Literature. — The first description of the plant is the one by De la 

 Pylaie in the " Flore de Terre Neuve." He describes in full the 

 morphology of the adult plant and that of several stages of develop- 

 ment. Pie emphasizes one point about the origin of the permanent 

 holdfast, which seems to have been entirely overlooked by later 

 writers. Areschong* was the next writer to add much to our stock 

 of information. He gives a number of very valuable details concern- 

 ing the size and form of some plants of different ages, and is the 

 first to announce the discovery of this species in Northern Norway 

 and to distribute specimens of it.f On the label of the specimen 

 distributed he remaiks, "cum speciminibus e Lapponica Rossica 

 nomine L. Bcerii, Post. & Rupr. acceptis melius quara cum specimini- 



* Obs. Phyc, Tart. III. p. 11. 



t Aig. Scand. Exss., No. 213, under tlie name of Laminaria lorea. 



