l8o THE BEGINNINGS OF LIFE. 



The celebrated Tiedemann also gave most definite 

 expression to his views on this subject when he said : 

 c Organized beings are produced from others like them- 

 selves, or else they owe their origin to organic sub- 

 stances in a state of decomposition/ Whilst, farther 

 on \ he adds : c The plastic power of the matter is not 

 extinguished after death; it preserves the faculty of 

 clothing itself again in a new form, and of displaying 

 its aptitude to manifest life. Death falls then only 

 upon the individual organizations, whilst the organic 

 substances entering into the composition of these 

 beings, continue able to assume form and to receive 

 life.' Respecting the conditions leading to, or prevent- 

 ing, this new assumption of living forms and properties, 

 Tiedemann says 2 : c The organic materials which be- 

 come separated from an organism preserve when they 

 are not reduced to their elements, or converted into 

 binary compounds by the action of chemical affinities 

 the property of reappearing, through the concurrence of 

 favourable external conditions (of heat, of water, of 

 air, and of light) under more simple animal and vege- 

 table forms varying always by reason of the influences 

 to whose action they are submitted.' 



Bremser and Burdach other German physiologists 

 were also firm believers in the doctrines of Hetero- 

 genesis, but as we have already referred to them 3 , we 

 will now pass to the consideration of M. Pouchet's 



1 ' Physiologie de 1'Homme,' Paris, 1831, torn. i. p. 100. 



2 Loc. cit., p. 104. 3 Vol. i. pp. 246 and 261. 



