November 15, 1895.] 



SCIENCE. 



649 



aid of very high magnifying jjowers. Tlie 

 movements we are considering in very 

 minute particles of living matter take a 

 general direction from center to circumfer- 

 ence, and the places of those which have 

 taken a centrifugal course are taken up by 

 the pabulum, the flow of which is centri- 

 petal. It is, in fact, in these centers, far 

 removed from our powers of vision, that 

 life power seems to be communicated to the 

 matter, and here the non-living matter be- 

 gins to live. Life causes elements, how- 

 ever strongly combined, to separate, and 

 overcomes the phj-sical and chemical at- 

 tractions of elements in combination. Life 

 is able to raise particles above one another 

 in a manner not explained. Of the rear- 

 rangement of the component atoms of mat- 

 ter, and of the alteration of their relation 

 to one another during the living state, there 

 can be no doubt, but how this is effected 

 has not j^et been ascertained. This rear- 

 rangement is different in the different kinds 

 of living matter and re.sults in the produc- 

 tion of certain special substances, constant 

 as regards living matter of the same kind 

 under the accustomed natural conditions. 

 So far, then, we seem to have arrived at 

 this, that the matter of the body actually 

 living can be distinguished from the ma- 

 terial which is formed by changes occurring 

 in any portion in which vital phenomena 

 have ceased. For instance, in the growing 

 ' cell ' of epithelium the central part is struc- 

 tureless and is alive, and its particles can 

 grow and multiply. The outer part has 

 structure, but no longer manifests vital phe- 

 nomena. It cannot produce matter like it- 

 self, or grow, or select nutriment, or exhibit 

 spontaneous movements. Just at the point 

 where the formed material and the living 

 matter touch, particles of the latter from 

 time to time cease to exhibit vital changes, 

 and the resulting products become formed 

 material which is added to that already 

 produced. Such changes occur everywhere 



in living organisms, from the first to the 

 last moment of existence, whether ' high ' or 

 ' low,' ' simple ' or ' complex.' Vital change 

 is one thing, physical and chemical change 

 another, and no particle of matter is the seat 

 of these two classes of changes at the same 

 moment. But there are other wonderful 

 powers associated with the living condition, 

 known to all but understood by no one, 

 some of which I shall now briefly refer to. 

 With regard to the marvellous power which 

 a speck of living matter may transmit with- 

 out loss to descendants during centuries, 

 only think of this: The oldest variety of 

 jjigeon, bred for many generations without 

 loss, and perhaps with improvement, of its 

 remarkable characteristics, and bear in 

 mind not only as regards color, form and 

 number of feathers, but widely diverging 

 from its original progenitors as to the char- 

 acters of bones, muscles, nerves and other 

 tissues; as to habits, manner and disposi- 

 tion, as to powers of flight — in fact, as to 

 many particulars which would lead us to re- 

 gard it as a true species far removed from 

 the rock pigeon — in short, having little in 

 common with that species — nevertheless 

 carries, apparently fixed and unalterable in 

 its organization, not a new tendency, but 

 an inalienable compulsion if left to nature 

 for its offspring to revert to the ancestral 

 characteristics; not immediately, but after 

 a few generations its descendants exhibit 

 the original specific characters, having lost 

 all traces of the variety which but a few 

 (often only three or four) generations be- 

 fore might have been regarded as a definite 

 species of pigeon. And, further, think of 

 this, that every rock pigeon, generation 

 after generation, has possessed deeply in- 

 grained, as it were, in its organization the 

 power of transmitting to descendants the 

 capacity of giving origin to any or several 

 varieties of pigeon that are known, and per- 

 haps to many more varieties not dreamt 

 of, and at the same time to every variety 



