THE LATENT VITALITY OF SEEDS. 107 



the open air, a second in a sealed glass tube containing common 

 air, and a third in a sealed tube containing pure carbonic-acid 

 gas. At the end of two years the seeds of the first lot had per- 

 ceptibly increased in weight, and nearly all germinated ; those 

 kept in confined air had increased less in weight, and fewer of 

 them germinated; the air inclosed with them in the tube had 

 changed in composition, having lost oxygen and gained carbonic 

 acid. Of those sealed up in carbonic acid, the weight had not 

 changed, and none germinated. 



While these results show that the seeds continued to lead a 

 retarded life in open and in confined air, it is possible that the 

 retarded life was only of short duration, and that it had ceased, 

 before the end of the experiment, to give place to a complete 

 stoppage of respiration, assimilation, and life. But to admit this 

 we have to suppose that the protoplasm in seeds in latent life 

 finally becomes wholly inert, while it preserves its composition 

 and its internal chemical structure. This view seems to be con- 

 firmed by a number of experiments and observations which I am 

 about to describe. 



I have already several times related experiments that prove 

 that seeds may be subjected to a very intense cold for many 

 hours in succession without losing their germinating faculty. A 

 recent experiment of this sort, made with M. Raoul Pictet's appa- 

 ratus and under his direction, proves that some peas and beans 

 and fennel seeds germinate quite well after having endured for 

 four days a temperature of - 200 C. ( 328 F.). The seeds had 

 not undergone any previous desiccation, and no precautions were 

 taken to adjust the depression of temperature. Others of M. 

 Pictet's researches have demonstrated that the chemical reac- 

 tions which take place at ordinary temperatures cease to be pro- 

 duced at very low temperatures, like those reached in the experi- 

 ments just mentioned. If this is so, we may suppose that the 

 protoplasm of seeds exists during these experiments in a condition 

 of complete inertia, without either respiring or assimilating. In 

 other words, life is then really stopped ; yet this does not prevent 

 their vegetating anew when the conditions of temperature and 

 moisture permit it. The seeds in these experiments were cooled 

 so very rapidly that it is natural to suppose that their protoplasm 

 was already quite inert before the test began. It would be hard 

 otherwise to explain its complete indifference to abrupt variations 

 of temperature, which would certainly have- been more harmful 

 if they affected protoplasm still active. 



Another experiment I have recently tried casts more light on 

 this point. Wrapping seeds of wheat, oats, fennel, and the sensi- 

 tive plant in packages of tinned paper and inclosing the whole in 

 a sheet- iron box, hermetically sealed, I placed them under the 



