NA TURE 



193 



THURSDAY, OCTOBER 22, 1914. 



EXPERIMENTAL AND PHILOSOPHICAL 

 BIOLOGY. 



(i) Experimental Zoologie. By Dr. Hans Przi- 

 bram. 4. \'italitat. (Lebenszustand.j Pp. 

 viii + 1794-X plates. (Leipzig and Wien : Franz 

 Deuticke, 1913.) Price 10 m. 



(2) Mechanism, Life and Personality. An Exami- 

 nation of the MecRanistic Theory of Life and 

 Mind. By Dr. J. S. Haldane. Pp. vii-139. 

 (London : John Murray, 1913.) Price 2s. 6d. 

 net. 



{^i I ^ ROM the point of view of an experimental 

 J. zoologist. Dr. Przibram has made a ver^- 

 valuable study of the distinctive characters of 

 organisms, which may be ranked in three groups 

 — structural, chemical, and functional. Organisms 

 have a heterogeneous structure, showing at least 

 cytoplasm and nucleoplasm, and they develop by 

 self-differentiation. Organisms also show chemical 

 differentiation, being built up of heterogeneous 

 proteids in a colloidal state. Organisms grow in 

 an active wav : they utilise food different from 

 themselves ; they multiply in a manner certainly 

 different from the division of crj'stals; they often 

 show apparently spontaneous movements ; and 

 they have an unusual power of preserx-^ing impres- 

 sions of previous states. It is interesting to 

 notice how little agreement there is as yet among 

 biologists as to the best way of stating these 

 general characters of organisms. Przibram 's is 

 marked by a desire to avoid any exaggeration of 

 the apartness of living creatures or any dis- 

 couraging of the methods of mechanistic inter- 

 pretation. 

 ; It is experimentally possible to mimic, with 

 inorganic materials, the growth, movements, and 

 even division of simple organisms, and a bowl of 

 gelatine may illustrate the power of retaining 

 traces of previous influences after the original con- 

 ditions have been restored. Many beautiful ex- 

 periments point to the conclusion that the 

 geometrical forms displayed by many organisms, 

 e.g. in their shells and skeletal parts, are expres- 

 sions of the properties of the "aggregation- 

 state " of the protoplasm. The polarity, likewise, 

 of an organism admits of interpretation in terms 

 of the " layering " or zonal distribution of different 

 kinds of substances, and in similar ways. 



The rapid advances of synthetic chemistn.- (only 



possible, however, through the directing intelli- 



, gence of the chemist), show that we must not 



ake too much of the chemical complexity of 



e proteids so characteristic of organisms ; the 



fficulty as to the optically active nature of vital 



rganic substances may be overcome ; and the fact 



NO. 2347, VOL. 94] 



that fermentation- and oxidation-processes are 

 slower when the living vehicles, e.g. yeast and 

 red blood corpuscles, are absent, may be due to 

 the greater concentration afforded by the organi- 

 sation of the living cells. Living implies action 

 and reaction between the organism and its 

 environment ; the continuance of the creature's 

 activity depends on its structural organisation 

 and on its specific series of chemical processes; 

 violent death ensues when changes in the com- 

 plex environment (chemical reagents, humidity^, 

 concentration, pressures, gravity, electricity, 

 radiant energies, and temperature) fatally disturb 

 the chemical processes, or break down the struc- 

 ture, or prevent the persistence of the organisa- 

 tion by disarranging the chemical routine. 



Przibram has made many observations on the 

 rate of grouch in different types, and his general 

 result takes us back to Herbert Spencer. A 

 doubling of the mass of the living cell leads to the 

 break-down of that cell, and the process is com- 

 parable to the " autokatalysis " observed in some 

 non-vital chemical transformations. Surely in its 

 movements, at least, the animal is spontaneous 

 and unique. But the author bids us consider all 

 the taxisms and tropisms — the inevitable re- 

 sponses which the creature makes in response to 

 external stimuli— of light, heat, pressure, humidity 

 and so on. He seems to us to lay on the shoulders 

 of taxisms and tropisms a burden heavier than 

 they can bear, and we do not think that what 

 Jennings observed of an amceba on the hunt can 

 be fully redescribed along these lines. It is plain, 

 however, that the interpretation in terms of 

 taxisms and tropisms must continue to be worked 

 for all it is worth until we get quite below the 

 stage of opinions. In answer to the common 

 criticism that we see different answers given by 

 the same or similar organisms to precisely similar 

 stimuli, Przibram admits that we must take 

 account of the physiological condition of the 

 organism as affected by previous experiences, 

 both personal and racial. This is a crucial {X)int 

 — whether inorganic bodies can be said to have 

 "duration" in Bergson's sense — ^the power of 

 continuing the past into the present. Przibram 

 admits that living creatures have the power of 

 registering the past in a notably high degree, but 

 he declines to credit them with the exclusive 

 possession of this quality, recalling for instance 

 the facility with which a piece of steel is magne- 

 tised after it has been magnetised before. 



As regards transformations of energy-, organ- 

 isms are marvellous engines, but they conform to 

 the laws of thermodynamics. The conclusion ar- 

 rived at is that we cannot assert that there oper- 

 ates in organisms any form of energy which is not 



I 



