132 GENERAL PHYSIOLOGY 



refined and careful methods of research. The majority of investi- 

 gators have always believed that in such dried organisms there is 

 really a complete standstill of life; but the objection has always 

 been possible that the metabolism in this condition may be so 

 slight that with the minuteness of most of the objects it cannot 

 be proved by the usual methods of investigation. The experiments 

 carried on recently by Kochs ('90) are likely to refute this ob- 

 jection completely. Dried animals, isolated upon a clean glass 

 slide, take in no solid or liquid food, and direct observation shows 

 likewise that no outgo of liquid or solid matters takes place. But 

 Kochs has demonstrated in the following way that a respiration, 

 i.e., an in-take of oxygen and an out-put of carbonic acid, is never 

 pi'esent. He selected for his experiments various plant seeds, 

 completely dried, and placed a considerable quantity of them in a 

 wide glass tube ; he extracted the air as much as possible by 

 means of the air pump and then sealed the tube by melting. If 

 only a slight metabolism were present in the seeds, with their 

 considerable quantity at least a trace of expired carbonic acid 

 could have been found. But, when after several months Kochs 

 investigated the contents of the tube by the most delicate methods, 

 he found not the slightest trace of expired carbonic acid or any 

 other product of metabolism. These experiments were repeated 

 always with the same result. Nevertheless, the seeds remained 

 capable of life and sprouted upon being sown. 



From the results of these experiments it can no longer be doubted 

 that in desiccated organisms there is a complete standstill of life. 

 Can organisms in this peculiar condition be termed dead ? In 

 reality they are lifeless but not dead, for anabiosis is possible after 

 the application of water, while nothing can bring dead organisms 

 back to life. The distinction between the dried and the dead 

 organism lies in the fact that in the former all the internal vital 

 conditions are still fulfilled, and only the external conditions in 

 part have disappeared, while in the latter the internal vital condi- 

 tions have experienced irreparable disturbances, although the 

 external conditions can still be fulfilled. 



Preyer illustrates this distinction very happily. He compares the 

 dried organism to a clock that has been wound but has stopped, so 

 that it needs only a push to set it going, and the dead organism to a 

 clock that is broken and cannot be made to go by a push. Hence 

 a sharp distinction must be made between dried and dead organisms. 

 But dried organisms cannot be called living, for they exhibit no 

 vital phenomena, and, as has been seen, vital phenomena are the 

 criterion of life. It is best, therefore, to apply to them the ex- 

 pression " apparently dead." Claude Bernard has termed the 

 condition of apparently dead organisms " vie latcntc " (latent life), 

 an expression which Preyer has replaced with " poteniielles Leben " 

 (potential life), in contrast to the usual or " aduelles Leben " 

 (actual life) of the normal organism. To use a German expression. 



