GENERAL OBSERVATIONS AND SKETCHES AFIELD 287 



I will recall some personal observations bearing on this 

 subject. I once entered an uncultivated meadow ^ to find a 

 strong wind blowing from the southwest, which came in almost 

 steady wilting blasts. It was seed distributing day par excel- 

 lence. The air was flecked with the flufly seeds of the field 

 thistles, which were accompanied with tops of grasses. These 

 seeds were flying as far as the eye could see and were being dis- 

 tributed broadcast. Many of the flower heads of the thistles 

 in some clumps of these plants were swelling to overflowing 

 with seeds, and the wind was in the act of carrying untold 

 thousands away to distant places. 



Again, here in a marshy swale, I also came upon some cat-tails 

 in the act of seed distribution. Stored within the magazines 

 were sufficient seeds to populate the marsh for acres. Simply 

 starting the seeds at one point was sufficient for the wind to 

 release showers of the little parachutes, which sprang into the 

 air and were carried away to distant points. 



Who can look upon the seed carriers of the milkweed or 

 dandelion without the thought at once arising of the marvel- 

 lousness of the physical adaptation for aerial travel displayed.'* 

 Did it take eons of time to perfect these structures.^ Or on 

 the basis of some remarkable mutations were these structures 

 hurried along in their evolution.'* It is obvious that these 

 questions cannot be explained in the indoor laboratory alone. 

 The pollen of many trees, such as the elm, poplar, and some 

 grasses, maize, and hazel, in which the stigmas are small and 

 inconspicuous, is carried by the aid of the wind and they are 

 thus pollinated. 



The sudden changes of temperature, as a control over life 

 processes, are all too apparent on every hand to ignore. The 

 destruction of small migratory birds that are caught in the 

 trend of a cold wave in the spring has been noticed from time 

 to time and is now common knowledge. The destruction of 

 insects that appear early in the spring, along with the injury 

 to flower buds by delayed frosts, are some of the physical effects 

 commonly noticed during certain seasons. 



Finally, elevation of temperature so as to produce the other 

 extreme of drought is also productive in destruction of many 

 ^ South of Jackson Park, Chicago, August 21, 1903. 



