No\-EMBER 1, 1899.] 



KNOWLEDGE 



241 



Founded by RICHARD A. PROCTOR. 



LONDON: NOVEMBER 1, 1899. 



CONTENTS. 



m PAGE 



The Mycetozoa, and some Questions which they 

 Suggest.— VI. By the Right Hon. Sir Kdwabd Fet, 

 D.C.L., ii.D., F.R.S., and Aqnb8 Fby 241 



Shells as Ornaments, Implements, and Articles of 



Trade. By R- Ltdekkek. [Illustrated) , ... 242 



Electricity as an Exact Science — VI. The Relation of 

 Modern Electrical Practice to its History, its 

 Units, and its Reasoning. Bv Uoward B. Little ... 246 



Ups and Downs in our Daily Weight. By W. W. 



WagstAfke, d.A., P.E.C.S. (Diagram) ... 247 



Is the Stellar Universe Finite ? By Gavix J.Bubns, b sc. 24S 



Photograph of Nebulas surrounding the Star D.M. 

 No. 1848 Monocerotis. By Isaac Robebts, d.sc, 

 F.E.s. [Plate) 249 



The November Meteors of 1899. By Edward C. 



Pickering. {Illustrated) ... ,., ... ... ... 250 



The '' Seas" of the Moon, what are they, and what is 

 the Cause of their Obscure Appearance? By J. G. 

 O. Tkpper ." ... 251 



Letters : A. K, Keane ; Lord Hampton j W. H. S. Mokck ; 



David Flaneby 2.51 



British Ornithological Notes. Conducted by Eabbx F. 



WiTHEBBT, P.Z.S., M.B.O.U 253 



Science Notes 253 



Recent Work of the United States Biological Survey. 



Bv Wilfred Maek Webb, f.l.s. .. . . ... ... 254 



Notices of Books 2.55 



BooK3 Received 258 



The Story of the Orchids. — III. By the Rev. Alex. S. 



Wilson, m.a., k.sc. (Illustrated) ... ... ... ... 259 



On the Duty of a Field Naturalist. By E. A, S. E. ... 260 



Microscopy. By John H. Cooke, p.l.s., f.o.s. 261 



Notes on Comets and Meteors. By W. F. Dennin&, 



F.B.A.S 262 



The Face of the Sky for November. By A. Fowlee, 



p.E.A.a 263 



Chess Column. By C. D. Locock, b.a 263 



THE MYCETOZOA, AND SOME QUESTIONS 

 WHICH THEY SUGGEST.-VI. 



By the Eight Hon. Sir Edwakd Fry, d.o.l., ll.d., f.r.s., 

 and Agnes Fry. 



THE INDIVIDUAL AND THE GENERATION. 

 — But it is time to return from the long digres- 

 sion into which we have been led by the unicellular 

 plants. If we consider ourselves or any other 

 higher organism, whether animal or vegetable, 

 and ask what is the individual and what is the generation, 

 we feel at first quite able to reply. We know that the 

 answers to these questions, when we seek to pursue the 

 enquiry to the bottom, involve other profound questions, 

 perhaps, insoluble difficulties, but on the surface the 

 answers are easy. 



If now we turn to the myxies and ask what is the 

 individual, the answer seems attended with no small 

 difficulty. In the swarm spore stage each separate proto- 

 plast is the individual ; each is capable of separate motion, 

 of digestion, and of multiplication. If we turn to the 



Plasmodium stage, the individual appears to be the entire 

 Plasmodium, built up as it has been by the union of a great 

 number of protoplasts, and not always the descendants of 

 the same parents ; if we take the sporangium stage, and 

 consider especially those cases in which each sporangium 

 stands on its own hypothallus, separated from the 

 hypothallus of its neighbours, the sporangium seems to 

 represent the individual. The life-circle of the myxie thus 

 exhibits a curious alternation of individualism and col- 

 lectivism — an harmonious solution of the problem raised 

 by the claims of the two principles which are found in 

 conflict in other organisms and states of society. 



Death and Reproduction. — We know that of late years 

 many interesting theories and questions have been pro- 

 pounded in relation to the great fact of Death, and that 

 the entrance of Death into the great chain of organic life 

 has been watched and studied. 



One view, to which Professor Weismann has given 

 great prominence, is that unicellular organisms possess an 

 unending duration, or, in other words, that though 

 susceptible of death by external force — as, e.g., by fire — 

 there is no natural death, but on the contrary a potential 

 immortality. He considers death, therefore, to have 

 come in with the multicellular organisms, and to take 

 place, as he says, " because a worn-out tissue cannot for 

 ever renew itself, and because a capacity for increase by 

 means of cell division is not everlasting but finite." 



Another view put forward (not by Weismann but by 

 Giitte) holds that death is always connected with re- 

 production, and is a consequence of the latter in the 

 lower animals. 



Lastly may be noticed another view, also propounded by 

 Gotte, that the first form of death is to be found in the 

 phenomenon known as encystment, which occurs when 

 an organism which has been alive and exhibiting the 

 phenomena of motion becomes stationary, develops a cyst 

 or coat around it, and after a period of rest and suspended 

 animation again revives when the favouring circumstances 

 occur. 



We thus state some of the views with regard to death 

 because we think that it will be found that the life-history 

 of the myxies throws some light upon them. 



Let us, however, first make these remarks : that in the 

 higher organisms we know of death in two forms, the 

 death of a part cast-off, as when we shed a hair or lose a 

 tooth, or as when a tree casts off its dead leaves ; and, 

 secondly, the death which affects the whole organism ; 

 and further that reproduction is in a great majority of the 

 higher organisms accompanied by the casting ofl^ of some 

 parts of the organism which have been devoted to the 

 nutrition and protection of the young offspring. In plants 

 we know how the floral envelopes drop off, and how the seed 

 vessels are allowed to fall and decay when their duty is done ; 

 and corresponding phenomena exist in the animal world. 



When the Plasmodium of the myxie has difl'erentiated 

 itself into the hypothallus and the sporangia, and these 

 have sent forth the spores, how are we to regard the 

 events which have happened ? Is the true view that a 

 parent organism has died ; that the empty sporangium 

 and the stalk, and the capillitium and the hypothallus 

 which are left behind to decay are the dead body of the 

 parent, and that the spores represent the new generation ? 



If this be the true view, and there seems much probability 

 in it, then we have clearly before us an unicellular 

 organism of the simplest kind, which exhibits the 

 phenomenon of death, and we cannot say with Weismann 

 that it is with the multicellular organisms that death for 

 the first time occurs. 



On this assumption it further follows that we have in 



