14 Mindeskrift for J. Steenstrup. XXXII. 



The following objections may be raised to this supposition. 



Let us consider at once the enormous quantity in which the Sargasso occurs. It 

 would seem strange if these masses of floating Sargasso were originally torn and 

 washed away from the shore, when we remember how proportionally few algæ are 

 met with floating in the northern seas, where the fucaceous alga-vegetation is so 

 much more luxuriant. If really the littoral, fixed types were the ones that were re- 

 presented at sea, the matter would not be difficult to explain, but it is not so. Once 

 in a while, and mostly near the coast, forms approaching the attached ones may be met 

 with; and moreover Ascophyllum from the coasts of the North Atlantic is said to have 

 been observed together with these ^). However the occurrence of these forms does not 

 seem to be of much importance since specimens of these algæ are scarcely more com- 

 mon in the Sargasso Sea than detached specimens of Fucus, Ascophyllum etc. in the 

 northern seas. 



If we accept the explanation that the Sargassum in the Sargasso Sea had been 

 torn loose from the shores, it must also be admitted that the constant absence of the 

 attachment-discs seems most remarkable, since i^MCws-specimens found floating in 

 northern seas are not unfrequently disc-bearing. 



As a support of this viewpoint I wish, furthermore, to emphasize the faet that 

 specimens torn loose from the shores are not in the same active state as the floating 

 ones. These specimens are for the most part old, and ready to die away^). 



^) Compare E. L. Bouvier in "Bull. de l'Institut Océanographique", No. 93, 1907, p. 36 and 

 H. H. Gran, in "The Depths of the Ocean", 1912, p. 335. Professor Gran has most kindly com- 

 municated me that Ascophyllum was found in the northern part of the Sargasso Sea, and rather 

 abundantly. 



-) Having made no observations myself as to the life history of the attached Sargassum, I 

 have consulted Professor Yendo who has followed the development of Sargassum in Japan in 

 many details, for many years. And Professor Yendo has most kindly communicated me the 

 following interesting remarks with the permission of communicating these as follow. He writes : 

 "From December till March the Sargassums are discharging the spores. Little difference of time 

 may be found according to the species. The spores become anchoraged. Young fronds with large 

 basal leaves are found in Aug. — Oct. They have no axillary, lateral branches. 



From the beginning of winter they grow up quickly giving rise to lateral branches, minor 

 branchlets etc, etc. untill the vegetation is at the highest vigorosity in April — May. They are yet 

 sterile. The basal leaves and the fulcrant leaves are all in a healthy condition. 



In summer time, in many species, the fulcrant leaves and the basal leaves which come out 

 in the first year drop away. In autumn the lateral branches develop further, forming receptacles. 

 The receptacles mature in winter between Dec. — April. Then the whole plant is uprooted and is 

 washed away. This takes place usually in the spring. There are certain fluctuations according to 

 species but in general this statement holds good for all species of Japan". 



I take for good that this observation holds good also with the development of the Sar- 

 gassum in the West Indies and elsewhere. Consequently the majority of the detached Sar- 

 gassum represents old individuals soon to die. That part of the detached Sargassu?n,'ne\er- 

 theless, may be able to reach the Sargasso Sea is not impossible; nor is it absolutely excluded 

 that some of the algæ may have the strength to remain active, and continue their growth. We 



