498 



NATURE 



[August i6, 191 7 



AccepUny this conception of the chemical constitu- 

 tion oi the essential Hving matter 'as a working hypo- 

 thesis, we know that in conjugation the one constitu- 

 ent of the germ cells contributed in an approximately 

 equal portion by both parents to the zygote, or fer- 

 tilised ovum, is the nuclear chromatin, and as heritage 

 of properties may corne equally from either parent, in 

 the nuclear chromatin must reside the main heritable 

 and character determining material. The conclusion 

 is inevitable that the essential biophoric molecules are 

 conveyed in the nuclear chromatin. The cell-wall, the 

 cytoplasm, and the nuclear membrane are all conserva- 

 tive agents, tending to preseVve the biophores from 

 sudden change from without, but, while conservative, 

 this system is exposed to constant change, particularly 

 in the more active tissue cells. The system is not 

 inert, but is constantly reacting with the external 

 medium in which the cell finds itself. The semi- 

 permeable cell membrane, while preventing the en- 

 trance of some substance, freely permits the entrance 

 of others, whether directly or after a preliminary dis- 

 sociation into smaller molecules by the action of extra- 

 cellular enzymes. Once foodstuffs are taken into the 

 cytoplasm they are, if necessary, broken down into yet 

 simpler molecules by intracellular enzyme action. 

 Foodstuffs are not utilised by the cell as such, but 

 only after dissociation and disintegration, and then 

 either by oxidation to supply energy or, on the other 

 hand, to be built up in growth. 



This matter of growth is wholly neglected by the other 

 biologists. They speak of inorganic bodies (crystals) 

 growing by agglutination, organic bodies by intussus- 

 ception. '"Intussusception," "imbibition," "intercala- 

 tion," and " interpenetration," are all inane terms ; 

 they cannot possibly explain how two molecules of 

 living matter appear where there was but one before, 

 two grains of wheat where but one was put into the 

 ground. Growth is one of the great underlying pheno- 

 mena of living matter, and zoologists and botanists 

 have in a simple Topsy-like manner been satisfied that 

 the phenomena occurs — and have left it at that. In- 

 crease in the amount of li/ing matter means multi- 

 plication of the molecules of living matter, and this 

 multiplication can only take place after the manner of 

 the growth of a crystal, by ions arranging themselves 

 into radicles, and radicles arranging themselves in a 

 particular order, until in orderly sequence the neces- 

 sary radicles become built up, identical in arrangement 

 with the pre-existing molecule, in association with 

 which the group has become developed. This con- 

 ception is materially aided by the recognition that 

 crystallisation does not of necessity demand the pro- 

 duction of rigid rectilinear figures. Lehmann in 1904 

 first directed attention to the existence of " fluid 

 crystals " ; in 1906 Adami and AschofT pointed out 

 that these fluid crystals are frequent in the animal 

 organism. As D'Arcy Thompson remarks, " the 

 phenomenon of liquid crystallisation dots not destroy 

 the distinction between crystalline and colloid forms, 

 but gives added unity and continuity to the whole 

 series of phenomena." 



Weismann's doctrine of the continuity of the germ- 

 plasm is erroneous ; it is not the germplasm which is 

 eternal ; merely there is a potential continuity of mole- 

 cular arrangement and constitution. The functional 

 and vegetative activities of the organism and the 

 cell, along with the essential nature of metabolism 

 and enzyme action, emphasise that these matters of 

 adaptation and evolution have to be approached from 

 the aspect of function and the dynamics of living 

 matter, rather than from the point of view of cell 

 statics. "Function precedes structure," and the study 

 of cell function must afford the kev. 



As regards the acquirement of the new power of 



NO. 2494, VOL. 99] 



digesting and utilising a foreign protein, it is seen 

 from what has been said that these proteins are com- 

 plexes of amino-acids ; and the number of the indi- 

 vidual amino-acids is limited.. Proteolytic enzymes, 

 already in existence, whether intra- or extra-cellular, 

 do not attack the foreign protein as a whole, but 

 must be regarded as dissociating certain everyday 

 amino-acids from the complex. But doing this, to 

 take the simplest case, the relative number of mole- 

 cules of the different amino-acids presented to the cell 

 may come to differ from the normal, or, again, the 

 simpler complexes due to the breaking down of the 

 foreign proteins may not be identical in constitution 

 with those which" the cell and its biophores had been 

 accustomed to utilise in growth. In either case the 

 constitution of the biophores may become altered as 

 they are .built up. Where enzyme-like bodies, such 

 as the toxins and phytotoxins, become introduced into 

 the cytoplasm, their toxic function must be regarded 

 as due to their power of dissociating the living mole- 

 cules, by detaching certain radicles. If the toxic 

 molecules be not present in too great a number, time 

 is given for the living molecules to attract and build 

 up again the lost radicles, and by the law of habit, 

 if this process be constantly repeated, particular 

 radicles are now to be built up in excess of the needs 

 of the cell, and, undergoing discharge, become the 

 antitoxin bodies of the blood and body fluids. 



That this conception of the mechanism of immunity 

 and progressive adaptation is substantially correct 

 was strongly supported by the long-continued and ad- 

 mirable studies of Prof. V. C. Vaughan, of the Uni- 

 versity of Michigan, and the later work of Abder- 

 halden, of Berlin, and his pupils. 



The prevalent conception of the Mendelians that the 

 parental properties remain segregated in the germ 

 cells is open to attacl<. In the zygote, the fertilised 

 germ cell, and in all the tissue cells derived therefrom, 

 it is inconceivable that two orders of biophores, or 

 active living molecules, can exist floating in a common 

 nuclear sap, undergoing growth, building up side- 

 chains and radicles, discharging certain of these, or 

 undergoing dissociation from time to time, without 

 the two reacting upon each other, and without a 

 certain amount of interchange, without the one having 

 a greater affinity for side-chains elaborated by the 

 other and building these into its system. There must 

 be this interaction, and at a slower rate, due" to their 

 more latent state, this same interchange must take 

 place in the germ cells. Along these lines it is still 

 possible to interpret the facts of Mendelism, and, 

 indeed, interpret not a few phenomena which by the 

 hypothesis of determinants fail to obtain explanation. 



Briefly, each species must be regarded as having 

 for its essential living matter a distinct organic com- 

 pound, a compound as distinct as any inorganic salt, 

 but differing from that. simpler salt in that whereas 

 the central ring, or chain, .is to be regarded as having 

 a relatively fixed constitution, the radicles composing 

 that ring or chain are to be regarded as capable of 

 attracting and then reproducing a series of side-chains 

 which may vary in constitution, so that within the 

 species there may be various strains, just as we may 

 speak of various strains of crystalline haemoglobin 

 obtained from different samples of human blood. 



It is possible to replace an impossible hypothesis 

 based upon supposititious independent and transposable 

 determinants by one based upon our present know- 

 ledg;-e of the composition and properties of the main 

 and outstanding constituent of living matter — the pro- 

 teins. To one who regards life, not from the morpho- 

 logical point of view, in terms of form, but from the 

 physiological, in terms of function, who regards life 

 as a moving equilibrium, who regards it as in essence 



