232 EXPERIMENTS ON TEMPERATURE BY EDWARDS AND COLIN. 



4. "If the numljer of seeds or grains be increased, and twenty-five be 

 employed instead of five, and brougbt into an atmospbere saturated with 

 moisture, without placing the e?;periment under a larger bell than in 

 the last instances, germination does not take place. 



5. " The same is also the case if the original number, for instance, 

 five grains are employed, and covered with a heU much larger, in which 

 case germination is very much retarded, if not prevented. 



6. " The circumstances which produce this retardation or hinderance 

 of germination, depend on the influence of temperature upon the 

 moisture of the air. 



7. "If the temperature is low, and undergoes little or no change, 

 germination will take place as soon under a small bell as under a 

 large one. 



8. "If the temperature is higher, moderate, and changeable, the 

 germination will be retarded under a large bell. 



9. " This occurs when during the daily change the temperature 

 increases, and the air has a tendency to depart firom a state of perfect 

 saturation, and if the space is great, the diffused vapour is in part 

 absorbed by the seed, and the air never reaches the point of 

 saturation. , 



10. " These effects probably do not .proceed from the fact that the 

 seed had not absorbed enough vapour ; in a low constant temperature 

 seeds absorb less water than in a higher, and in the first case germina- 

 tion takes place, and in the last it is retarded or entirely prevented. 



11. "These remarkable facts are produced by the air not being 

 sufficiently -saturated with vapour to allow of the necessary application 

 of moisture to the external membrane of the seed. 



12. "In germination, two principal conditions with regard to the 

 vapour are required to take place ; first, that the seed absorbs enough 

 vapour for the function of nutrition ; and second, that the external air 

 be saturated with sufficient vapour to soften sufficiently the test* of 

 the seed. 



13. " Through the simultaneous action of water and vapour, germina- 

 tion constantly takes place, and earlier where the air is saturated with 

 moisture.' 



14. " With regard to the application of these principles to seeds 

 sown in different kinds of soil, the authors found that germination took 

 place by the agency of vapour when seeds were placed in sand and clay, 

 but in both cases the process was longer, especially in the clay, which 

 absorbed the vapour slowly, and imparted it slowly to the seeds." — 

 German Translation. 



THe foregoing observations apply to seeds in a perfect state 

 ,of health ; Tvhen they have become sickly or feeble, from age 

 or other causes, some precautions become necessary, to which. 



