'■iO STUDY OF COMMON PLANTS. 



accompanied bj^ a rise of temperature, and chemical ex- 

 amination indicates absorption of oxygen and exhalation 

 of carbon dioxide ; in other words, respiration is going on. 

 The length of time during which seeds retain their 

 vitalitj* has been the subject of much discussion. Stories, 

 Dniationof frequently repeated, of the growth of grain 

 vitality, many centuries old, taken from Egyptian tombs, 



and of raspberry seeds from a Roman skeleton in England, 

 etc., are generally discredited, for the reason that sufficient 

 proof is lacking. On the other hand, a series of experi- 

 ments, conducted for a long period by a committee of 

 the British Association for the advancement of science, 

 shows that some seeds have certainly retained their ca- 

 pacity for germination fi'om twenty to forty years, and 

 even longer.^ 



^ Report of British Association, 1857, Dublin meeting. 



