POLLEN : ITS DEVELOPMENT AND USE. 343 



flowers produce an apparently wasteful amount of pollen and take 

 the chances of a cross, than to be more economical and be perpet- 

 ually self-fertilized. 



A few words now as to the movements of the stamens in con- 

 nection with the ejection of the pollen. The contrivances for this 

 are various. In the barberry (Fig. 9) the anthers are provided 

 with valves which fly up and throw out the pollen when the base 

 of the filament is touched. In the sheep-laurel (Kalmia, Fig. 10) 

 the anthers are lodged in little pits on the corolla lobes, and the 

 filaments are in a state of tension. The anthers open by terminal 

 pores, and when the base of the filament is disturbed the anther 

 is released from the pit and flies forward, this movement throw- 

 ing the pollen out of the pores at the apex. The anthers of the 

 heather {Erica tetralix, Fig. 11) are provided with j>rocesses pro- 

 jecting backward and nearly touching the sides of the corolla 

 tube. As they have 

 terminal pores, and 

 are pendent, when 

 the processes are jos- 

 tled, as they would 

 be by the visits of 

 insects, a shower of 

 pollen falls upon the 

 visitor. Lastly, in 



the Sage (Salvia, Natural position. Wnen moved by insect. 



Fig. 12), the anthers FrG 12 ._ Salvia . (After Lu bbock.) 



are separated by a 



long connectile which is hinged at the top of the filament in such 

 a way as to cause one of the anthers to come forward and down- 

 ward when the other one is disturbed and pushed backward. 

 They are at the same time so placed in the corolla tube that the 

 movement is inevitable, and the distribution of the pollen certain, 

 when an insect visits the flower. 



Instances have been often reported in which fisli have been frozen in cakes of 

 ice and recovered their vitality when thawed out. Fish are mentioned in Frank- 

 lin's journey to the polar seas that froze as fast as they could be taken from the 

 net, so that they were split open with a hatchet, and yet became lively when placed 

 before the fire. The phenomenon is referred to by Izaak Walton. Mosquitoes are 

 said in the Quarterly Review to have been frozen on to the surface of a lake in the 

 evening, and thawed again by the morning sun into animation. Alpine climbers 

 sometimes pick up butterflies lying frozen and brittle on the snow-, which revive 

 and fly away when taken to the lower warmer regions. Insects which habitually 

 hibernate, as larva? or pupaa, do not suffer from being frozen for a lengthened 

 time; but they suffer in open winters from frequent alternations of wet, warmth, 

 and cold. 



