362 



NA TURE 



\August 15, 1889 



depths, currents, passages, and contour lines, Mr. Agassiz 

 is well qualified to enter on a discussion of the relations 

 of the American and West Indian fauna and flora, which 

 he does in a most suggestive and instructive chapter. 

 He says : — 



" The deep soundings south of Cuba, between that 

 island and Yucatan and Jamaica, do not lend much sup- 

 port to the theory of an Antillean continent as mapped 

 out by Wallace, nor is it probable that this continent had 

 a much greater extension in former times than now, judg- 

 ing from the depths found on both sides of the West 

 Indian Islands. This would tend to prove the want of 

 close connection between the West Indian Islands and 

 the adjoining continent. It leads us to look for the origin 

 of the fauna and flora of those islands to causes similar 

 to those which have acted upon oceanic islands. The 

 proximity of these islands to a great continent has, 

 moreover, intensified the efficiency of these causes." 



Since the return of the Challenger, the existence of 

 Tertiary continents in the Atlantic, Indian, and Pacific 

 Oceans does not appear to have been seriously advocated. 

 These views have been generally replaced by that which 

 looks upon the continents and ocean basins as holding 

 positions of great permanence on the surface of the earth. 

 Mr. Agassiz adopts this latter view, and illustrates it by 

 special reference to the geological structure of the Ame- 

 rican continent and its adjoining oceans. In discussing 

 this matter, he expresses the opinion that the " Blake 

 Plateau" was once within the 100- fathom line, and that 

 it has been cut away to its present depth of 500 or 600 

 fathoms " by the action of the Gulf Stream acting upon 

 the ' Blake Plateau ' from a geological time which we 

 can trace with a certain degree of accuracy." This is a 

 most important conclusion, but I cannot think it will be 

 accepted till more evidence of the action of oceanic 

 currents at these depths can be produced. The deposits 

 I have examined from the bed of the Gulf Stream are 

 principally composed of the shells of pelagic Foramini- 

 fera, Pteropods, and other organisms living in the present 

 seas of the region, together with much glauconite and many 

 phosphatic concretions. These would lead one to think 

 that the bed of the Gulf Stream was now growing upwards 

 by these accumulations, rather than being washed away. 



All the new and valuable observations on the tem- 

 peratures of the West Indian seas and on the Gulf 

 Stream are presented to the reader with a wealth of 

 illustration in the way of diagrams and maps that leaves 

 little to be desired, and the chapters on these subjects 

 give to the physical geographer many much-needed data. 



Mr, Agassiz has long been known to the scientific 

 world for his special researches on the pelagic animals 

 of the eastern North American coasts, conducted chiefly 

 at Newport since 1866. It was therefore to be expected 

 that his observations in this direction would be attractive 

 and important. Nearly allthe principal organisms met 

 with in the tow-nets are illustrated in the long chapter 

 devoted to this subject, and the naturalist will here find 

 much new matter and many novel views concerning the 

 origin of this fauna. He says : — 



" It seems most natural to look upon the pelagic fauna 

 of to-day and that of former geological periods as made 

 up of embryonic types removed from the influences 

 necessary for their full development, even after a time 

 reproducing themselves as other larval forms are now 

 capable of doing. But to consider that the littoral forms 



were developed from pelagic types, as has been suggested 

 by Moseley, does not seem to be warranted by the 

 embryological history of marine invertebrates." 



The chapters on marine formations, deep-sea deposits 

 and deep-sea fauna contain the latest information and 

 views as to their origin, and the first volume is concluded 

 with a chapter on the physiology of deep-sea life, deahng 

 with the gases in sea-water, the eff'ects of pressure and 

 temperature, phosphorescence, effects of the absence of 

 sunlight, colours of deep-sea animals, source of their 

 food, and other kindred relations. 



It is now recognized that the inhabitants of the abysmal 

 regions differ more from the shore species than they do- 

 from one another. Perhaps the most striking character- 

 istic of deep-sea species is that they live in a region 

 where there is no plant-life, and that their food consists 

 primarily of the dead remains that fall to the bottom 

 from the surface. All these animals, therefore, either live 

 by eating the mud or ooze of the bottom, or by devouring 

 each other. It appears to me probable that these deep- 

 sea animals are derived from the shore ones, some species 

 descending into these deep regions and establishing a 

 home there at each geological period, while the forms 

 from which they were derived have died out in the shal- 

 lower waters. 



This and all similar questions Mr. Agassiz discusses in 

 his second volume, where he deals specially with the 

 West Indian fauna of the deep sea. He writes : — 



" We may safely assume that but little will hereafter 

 be added to our notions of the association of the sponges, 

 polyps, corals, echinoderms, Crustacea, and mollusks, 

 comprising the West Indian deep-sea fauna, and making 

 it in certain groups by far the richest in the world. The 

 number of new forms from the West Indian region con- 

 stitutes such a vast addition to our knowledge of the 

 principal classes of invertebrates of that fauna as to 

 revolutionize our ideas of geographical as well as of 

 bathymetrical distribution. No other region of the 

 ocean has yielded so abundant a harvest." 



I should think that in proportion to the number of 

 dredgings, the regions in the Southern Ocean investi- 

 gated by the Challc/tger, or off the north of Scotland 

 worked over by the Porcupine and Triton, might be held 

 to be quite as rich as those of the West Indian Islands. 

 It is to be hoped that this will be shown before long 

 by an expedition thoroughly equipped for examining the 

 deep waters around Britain. 



In a series of nine chapters in his second volume Mr. 

 Agassiz attempts for the first time to give a general 

 account of the deep-sea fauna in the areas explored by the 

 Blake, commencing with the fishes, and ending with the 

 Protozoa. In this he has been remarkably successful b} 

 the help of numerous illustrations. For details the reader 

 must be referred to the volumes themselves, which will be 

 widely consulted, and will well repay all who give them 

 attentive study. John Murray. 



RANTS "KRITIK." 



Kanfs Critical Philosophy for English Readers. By 

 J. P. Mahaffy and J. H. Bernard. (London : Mac- 

 millan and Co., 1889.) 



THE abundance of Kantian literature within recent 

 years shows no signs of abating. In German) 

 itself there is quite a school of students who have taken 



