138 TALKS AFIELD. 



as in Fig. 94, a. So different in appear- 

 ance were these thistle 

 fA\p|!f^^ seeds, with their pappus 

 jj 5 iill standing erect, from 



'^&^f,/^-<::-^ those which were float- 

 ^Smr^^ ^"^ ^^ *^^^ centre oi 

 round balloons all over 

 ^'^- ^^ the fields that I could 



scarcely believe them the same. How could 

 they get out of the tight thistle head? I 

 carelessly laid my thistle head in a sunny 

 window, and soon forgot it. An hour later 

 I was surprised to find that a complete met- 

 amorphosis had taken place. The head had 

 spread open in every direction, and the seeds 

 were actually crawling out of it. A closer 

 observation at once revealed the nature of 

 the movement. Under the influence of the 

 heat the head had spread open ; then the 

 pappus on every seed began to spread, more 

 rapidly in the centre of the head where the 

 heat was more directly concentrated. The 

 spreading of the pappus plumes loosened 

 the seeds and forced them apart until some 

 of them were quite out of the head. But 

 the most striking part of the performance 

 occurred after the outer pappus plumes on 

 each seed had reached a horizontal position. 



