18 



BIOLOGICAL RESULTS OF LAST CRUISE OF CARNEGIE 



PACIFIC COLLECTIONS 



A collection was made in April 1929 on the reef at 

 Apia, on Upolu of the Samoan group (bottle 8169). Sev- 

 eral entire specimens of the bright green pom pom-like 

 Chlorodesmls comosa Harv. et Bail, were found in the 

 bottle: two fairly large specimens of the light green, 

 areolate Dlctyosphaeria australis Setchell; and two spec- 

 imens of a light red, flat, and laciniately much branched 

 alga with the surfaces covered with low, blunt papillae, 

 which seems to be referable to Meristotheca papulosa 

 (Mont.) J. Ag., but with more the habit of Halymenia 

 ceylonica Harv. Unfortunately it is sterile. 



Between stations 115 and 116, latitude 38° 06' north 

 and longitude 146° 53' east (sample 699), the 1/2 meter 

 net caught a couple of small fragments of what seems to 

 be the Japanese brown alga, Cystophyllum hakodatense 

 Yendo, a very probable find. 



Around Easter Island, south of the equator, three 

 samples containing Sargassum prove to be the most in- 

 teresting and novel catches of the whole plankton collec- 

 tions, so far as the macroscopic marine algae are con- 

 cerned. The samples (309, 317, and 318) represent dif- 

 ferent phases of attached and floating forms, and seem 

 also to have a definite bearing on the "Sargasso Sea" 

 type of situation in the Indo-Pacific Ocean area. The 

 specimens, which are excellent as such material goes, 

 are closely related to a species group to which may be 

 referred Sargassum stenophyllum J. Ag. (non Martius), 

 S. lanceolatum J. Ag. (non Greville), and S. Skottsbergil 

 Sjostedt. 



Sample 309 of the Carnegie collections was brought 

 up from a depth of 15.4 fathoms by the snapper. It shows 

 several plants. Two of these are species of Zonarla, 

 probably to be referred to Z. variegata (Lam'x) Mert. 

 and to Z. crenata J. Ag.; the former a prostrate speci- 

 men, the latter represented by two upright specimens. 

 Unfortunately, all the Zonarla plants are both young and 

 sterile. There are, in addition, several specimens of 

 Sargassum, two of which lack only the very holdfasts 

 themselves of being complete. They show short (1 to 2 

 cm in these specimens), relatively stout, cylindrical, 

 erect primary axes with sparse lateral tubercles, and 

 with the primary branches grouped about the apex. The 

 primary branches are compressed (even to flat below), 

 and the leaves and secondary branches are arranged dis- 

 tichously. All branches show marginal cryptostomata. 

 The leaves are linear -lanceolate, sharply cuneate at the 

 base, and attenuate above to a sharper or a somewhat 

 obtuse apex. The margins are all sharply and rather 

 coarsely dentate, with teeth one- to two-fifths the diam- 

 eter of the leaf, projecting outward and sharply forward, 

 and broadly or narrowly triangular in outline. The costa 

 is stout and conspicuous below, broadening toward the 

 upper part to the point of vanishing somewhat below the 

 apex. The cryptostomata are smaller, less prominent, 

 and scattered, in the lower leaves, becoming larger and 

 more conspicuous above, arranged uniseriately on each 

 side of the costa, frequently in pairs along it. The 

 leaves are short-ly petiolate. The secondary branches 

 are frequent (at intervals of approximately I cm) and 

 short (2 to 4 cm long) as compared with the primary 

 branch (up to 30 cm long), whence they arise. Only one 

 of the plants shows receptacles. These are cymosely 

 branched, about 1 cm in height. The individual branch- 

 lets are arranged dichotomously below, but subdichoto- 



mously, almost racemosely, above, are compressed cy- 

 lindrical, tapering above, and alternately torulose as 

 the individual conceptacles mature and become protu- 

 berant. All the conceptacles show antheridia only, thus 

 suggesting a dioecious species. 



Sample 317 is made up of about sixteen fragments, 

 evidently of the same species as those of sample 309. 

 It was collected about two miles northeast of Easter 

 Island, in latitude 27° 25' south and longitude 109° 25' 

 west, from the surface. Axes and leaves of these tips 

 of plants agree with those of sample 309. Evidently 

 they had not been long detached, since in color, consist- 

 ency, etc., they seem not at all modified. The recepta- 

 cles, however, are varied. Both antheridial and oogoni- 

 al receptacles are present, but on different fragments, 

 the majority being antheridial. The antheridial recep- 

 tacles of these plants are similar in shape and branch- 

 ing to those of sample 309, except that some of them are 

 more elongated (up to 1.5 and 1.75 cm) and very slender. 

 The oogonial receptacles, though still of the Malaco- 

 carpic, or unarmed (i.e. without teeth or spines) type, 

 are very different from the long linear antheridial type. 

 They are shorter (about 5 mm high) and less divided 

 (only once or twice dichotomously cleft or lobed), the 

 divisions being narrowly ellipsoidal fusiform, with the 

 conceptacular openings broader and more gaping. In 

 the Carnegie specimens, only the apical conceptacles of 

 each receptacle show oogonia, but the lower concepta- 

 cles show swollen structures such as are found in an- 

 theridial conceptacles. 



Sample 318 was taken from floating masses (sur- 

 face) about 8.5 miles southeast of Easter Island. The 

 masses show the peculiar yellow of the Sargassa of the 

 Sargasso Sea and might readily be taken for similar 

 masses of Sargassum natans (L.) Meyen. The short in- 

 dividual fragments (up to 10 cm long) seem likely to 

 have arisen in the floating state. The stems, leaves, 

 bladders, and receptacles, however, are practically 

 identical in the principal details of their structure with 

 those of samples 309 and 317. The costae (or midribs) 

 of the leaves, however, seem stouter, the cryptostomata 

 fewer and less conspicuous (at least in some of the frag- 

 ments) and there are encrusting bryozoans, etc., on 

 them similar to those occurring on the floating frag- 

 ments of S. natans in the Sargasso Sea of the Atlantic 

 Ocean. 



There does not seem to exist for the Pacific or In- 

 dian oceans any real approximation to the Sargasso Sea 

 of the North Atlantic. In the extreme south Pacific a 

 pleuston, often very conspicuous and of large masses, 

 is frequently met with, especially in the vicinity of Cape 

 Horn and the west Patagonian coast. This has for its 

 chief constituent, plants of Macrocystis. In the extreme 

 northern Pacific Ocean, vast floating masses of Nereo- 

 cystis or of Alaria fistulosa may be seen, particularly 

 near Unimak Pass, in the Aleutian Islands. These 

 masses, often of several acres in extent, are made up 

 of stems and the huge terminal bladders of the Nereo- 

 cystis or of the long leaves of the Alaria with their in- 

 terruptedly swollen and inflated midribs. Both the 

 Macrocystis formations (which may be true pleustoi^ 

 and the floating masses of Nereocystis or of Alaria (not 

 true pleustons) are characteristic of cold waters, but 

 waifs from them seemingly stray into the edges of trop- 



