PLANKTONIC STUDIES. 619 



with life'" (p. 2iS). This astonisliing wealth of i)laukton was observed 

 in the wliole breadth of the Atlantic tropical zone in Angiist and Sep- 

 tember, 1873; bnt it was not less than that passed by the Gltnllenger 

 on her return in March and April, 187G, in the eastern part of the same 

 region, between Tristan d'Aonnha and Cape Yerde. "When the water 

 was calm, an extraordinary siiperabnudance of pelagic life appeared at 

 the snrface. O.^clllatorice covered the sea for miles, and vast quantities 

 of Badiolaria [Gollosoun) filled the nets" (p. 930). With those and 

 other accounts by the Challenger, those of tiie Vettor Flsani quite agree. 

 " T'nc zone of eiimitorial calms is out ofaUjjrojjorlion rich in organic life. 

 Sometimes the' water seems coagulated, jelly like, even to the touch. 

 It is impossible to describe the quantities of variously colored forms" 

 (8, p. 31). Chiercliia enthusiastically describes the wonderful spectacle 

 which the luminous ocean furnishes at night — "a sea of light which ex- 

 tends to the whole horizon" (pp. 32, 53, etc.). The iiumerous plankton 

 samples wiiich I myself have investigated from the Atlantic tropical 

 zone show for the most part an extraordinarily rich composition, par- 

 ticularly those between Asceusion and the Ganarj? Islands {Challenger 

 stations 315 to 353), above all the two equatorial stations 317 and 318, 

 which, like the Canary currents, which I studied for three months at 

 Lanzarote, whose fabulous wealth I have already mentioned, also belong 

 to the region of the iroplcal trades-drift. 



Tiie quantity and wealtli of forms of the plankton in the tropical 

 zone of the Pacific Ocean is not less than in the tropical region of the 

 Atlantic and Indian oceans. In the most diverse parts of this region 

 the Challenger sailed tlirough "thick banks of pelagic animals," 

 Between the iSTew Hebridiis a id ]S"ew Guinea "the surface of the water 

 and its deeper levels swarmed with life. All the common tropical 

 forms were found in great abundance. The list of genera of animals 

 was about the same as in the Atlantic tropical region (i)p.218, 219), but 

 it showed consideraMe diiference in the relative abundance of species''^ 

 (0, p. 521). Among the Philippines the water showed "a quite uncom- 

 mon quantity and variety of oceanic surface animals" (p. CC2). On 

 the voyage from the Admiralty Islands to Japan the oceanic "fauna 

 and flora of the surface was everywliere especially rich and varied. 

 In the neighborhood of the equatorial countercurrents, between the 

 equator and the Carolines, pelagic foraminifera and mollusks were 

 taken iii such quantities in the surface net that they surpassed all 

 earlier observations," etc. (p. 73S). On the voyage through the ce«f>v(i 

 part of the tropical Pacific, from Honolulu to Tahiti, between 20° ]Sr. 

 hit., and 2i)'^ S. lat., "the catch of the tow net was everywhere very 

 rich. The superahundance of organic life in the equatorial current and 

 countercurrent is very noticeable, as well with reference to the number of 

 species as of individuals''' (p. 776), From this wonderfully rich region, 

 which of all parts of the tropical ocean is farthest removed from all 

 continents, came the absolutely richest plankton samples which I have 



