Page:Popular Science Monthly Volume 39.djvu/357

Rh flowers produce an apparently wasteful amount of pollen and take the chances of a cross, than to be more economical and be perpetually self-fertilized.

A few words now as to the movements of the stamens in connection 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 throwing the pollen out of the pores at the apex. The anthers of the heather (Erica tetralix, Fig. 11) are provided with processes projecting backward and nearly touching the sides of the corolla tube. As they have terminal pores, and are pendent, when the processes are jostled, as they would be by the visits of insects, a shower of pollen falls upon the visitor. Lastly, in the Sage (Salvia, Fig. 12), the anthers 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 downward 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 fish have been frozen in cakes of ice and recovered their vitality when thawed out. Fish are mentioned in Franklin'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 larvæ or pupæ, do not suffer from being frozen for a lengthened time; but they suffer in open winters from frequent alternations of wet, warmth, and cold.