October 27, 1892] 



NATURE 



623 



each instance referring to the original memoir, and collating the 

 worm with the author's description. 



A List of Knaivn British Earthworms. 



2 Rubellus 



3. Purpureas 



4. Kubescens 



Allolobophora. 



§ I. Luinbricoidea. 



5. Longa 



6. Profuga 



7. Complanata 



§ 2. Mucida. 



8. Chlorotica 



9. Trapezoidea 



10 Turgida 



11. Foeiida 



12. Mucosa 



13. Cambrica 



§ 3. Dendrobxna, 



14. Boeckii 



15. Subrubicunda 



16. Arborea 



17. Eiseni 



18. Constricta 



19. Celtica 



Aluhus. 



20. Tetraedrus 



" Syst. Nat.," ed. x., torn, i., 



647. . . 

 " FamiliederRegenwiirmer." 

 Ofversigt afK. Vet.-Akad. 

 Linnean Society, 1892. 



Zeitsckrift f. ]Viss. Zool. 

 " 1 Lumbricidi del Pie- 



monte." 

 Ann. des Sc. Nat., 2nd sen, 



Cuv , "Hist, des. Prog. Sc. 



Nat.," ii. 

 Ann. des Sc. Nat., 2nd sen, 



viii. 

 Ofversigt af K. Vet.-Akad. 

 Cuv., "Hist. Pr. Sc. Nat.," 



torn. iv. 

 Ofversigt afK. Vet.-Akad. 

 Nature, current issue. 



Ofversigt af K. Vet.-Akad. 



"Syst. Geogr. Overs, over 



de Nord. An." 

 " I Lumbricidi del Pie- 



monte. " 

 Bolletino dei Miisei di Zoo. 



ed Anat. 



Cuvier, "Hist. des. Prog.," 

 ..torn, iv., p. 17. 

 Ofversigt af K. Vet.-Akad. 



I 



When Darwin wrote his work on " Vegetable Mould," he as- 

 sumed the existence of eight or ten species of earthworm in 

 Great Britain. We now find a score of well-defined species, to 

 which I have no doubt we shall be able to add a few others 

 when the montane and out-of-the-way habitats have been ex- 

 plored. I shall be happy to receive consignments of living 

 worms from any part of the kingdom, packed in tin boxes lightly 

 filled with soft moss, and addressed The Grove, Idle, Bradford. 



HiLDERic Friend. 



THE PROBLEM OF MARINE BIOLOGY.^ 

 TN common with the other branches of biological science, the 

 ^ study of marine life has made wonderful advances in the 

 past half century, and we now begin to get a proper conception 

 of the vastness and importance of this realm of nature. 



The study of marine life has been compassed by serious diffi- 

 culties ; on shipboard it is impossible to examine in the living 

 condition the enormous quantity and endless variety of forms 

 brought up at a single haul of the net or dredge ; and the old 

 method of merely dropping the specimens into vials of alcohol 

 resulted in vials of wrath to the naturalist who later studied the 

 creatures in hopes of gaining from the distorted relics some 

 knowledge of the normal appearance and anatomy. Now all 

 this is changed, and by aid of certain chemical reagents most 

 animals can be killed and preserved in a manner very satisfac- 

 tory for study of their gross and microscopical anatomy, and 

 hence the material collected can be examined at leisure in per- 

 manent laboratories with results corresponding to the better 

 facilities. There has, too, been a great lack of suitable and 

 accurate collecting apparatus. The early method was to scoop 

 up a quantityof sea water and then tediously examine it in small 

 quantities under the microscope. In 1845 Johannes Midler, the 

 great pioneer of marine biology, conceived the idea of condens- 

 ing into a small volume of water the forms which would be found 

 in a very great area. This resulted in the invention of the 

 "MUtler Net," a small gauze net which is drawn through the 

 water, entangling in its meshes the very minute and delicate or- 



' Reprinted from the American Naturalist for October, 189a. 



NO. 1200, VOL. 46] 



ganisms. For a long time Miiller and his students pursued the 

 study of marine forms, and at length came the discovery that the 

 marine fauna and flora was directly comparable to the terrestrial. 



Yet little is known of the laws of the distribution of marine 

 life. The laws of the distribution of the terrestrial fauna and 

 flora have been formulated for animals in the classical works 

 of Wallace and for plants by Griesbach. The famous Chal- 

 lenger expedition (1873-1876), under the direction of Sir 

 Wyville Thompson and Dr. John Murray, has given us the 

 largest conception of the wealth of marine life, and has laid the 

 foundations for the study of the marine forms both at the surface 

 and in the depths of the ocean. Dr. Murray in his preliminary 

 report called particular attention to the enormous wealth of or- 

 ganic life not only at the surface, but also many hundred fathoms 

 below. He says that when living forms were scarce on the 

 surface the tow net usually disclosed very numerous forms be- 

 low, even to a depth of 1000 fathoms or more. In the North 

 Pacific Ocean, the discovery was made that zones of definite 

 depth are characterized by animals and plants peculiar to them. 

 The tow nets sunk to 500, 1000, or 2000 fathoms brought up 

 forms never found within 100 fathoms of the surface. The ani- 

 mals characteristic of these different depths are, for the most 

 part, of the class of Radiolarians, those microscopic organisms 

 whose silicons skeletons form much <^f the soft ooze which car- 

 pets the bottom of the deep sea. Prof. Haeckel, by study of 

 this material, was led, in his monumental work on the Radio- 

 laria, which forms a part of the " Report of the Challenger," to 

 the recognition of three groups, {a) pelagic, swimming at the 

 surface of the calm sea ; {b) zonary, swimming in definite zones 

 of depth (to a depth of more than 20,000 feet) ; {c) profound (or 

 abyssal) animals swimming immediately over the bottom of the 

 deep sea. In general the different characteristic forms corre- 

 spond to the different zones (up to 27,000 feet). 



The existence of this intermediate pelagic fauna was called in 

 question by Alexander Agassiz, on the ground of the liability 

 of error in using the ordinary open net instead of one which 

 could be closed at a definite depth and then drawn up ; and 

 more particularly upon the ground of his own experiments made 

 in 1878 on the Blake expedition. He believes that the 

 great bulk of the ocean contains no organic life at all, that the 

 surface fauna of the sea is limited to a relatively thin layer, and 

 that there is no intermediate layer, .so to speak, of animal life 

 between the fauna of the bottom of the deep sea and of the 

 surface. 



Agassiz's results are contradicted by those of Chierchia on 

 the Italian corvette Vettor Pisani. With the closable net 

 invented by Palumko he brought up an astonishing quantity 

 and variety of forms of life from different depths, even up to 

 4000 metres. Prof. Carl Chun, with an improved closable net, 

 studied the marine fauna and flora of the Gulf of Naples. He 

 formulates his results as follows : (i) That part of the Mediter- 

 ranean investigated shows a rich pelagic life even to a depth 

 of 1400 metres, as well as at the surface. (2) Pelagic animals, 

 which during the winter and spring appear at the surface, at 

 the beginning of summer seek the depths. (3) At greater 

 depths pelagic animals occur, which hitherto have seldom or 

 not at all been observed at the surface. (4) A number of 

 pelagic animals during the summer remain at the surface and 

 never go into the depths. From his observations upon the 

 vertical distribution of marine life he was led to remark that the 

 surface fauna was apparently only the advance guard of the vast 

 army below. His conclusions were confirmed by observations 

 made during a trip to the Canary Islands, and agree with those 

 made by Prof. Haeckel twenty years before. 



Prof. Hensen, of Kiel, has for several years past been study- 

 ing the phenomena of pelagic life with a view of ascertaining 

 its relations to the fisheries question. He has proposed the 

 term Plankton (from irXd.voft.ai, to wander) to designate this 

 world of marine life. Prof. Haeckel agrees with this and adds 

 Planktology, that branch of biology which deals with the study 

 of the Plankton. Prof. Hensen hopes to gain valuable infor- 

 mation upon the phenomena of marine life by a careful mathe- 

 matical estimation of the number of individuals in a given bulk 

 of water. Presumably from this and other data some knowledge 

 may be gained of the quantity of life which any definite area of 

 the sea is capable of sustaining. 



Prof. Ernst Haeckel, of Jena, has lately published an admir- 

 able rhumi oi our knowledge of pelagic life, and has made a 

 very di.stinct advance by formulating some of the laws which 

 govern its distribution. He has probably done more than any 



