1 882.] Forests — their A ate and Rainfall. 23 



own -observations tend to confirm the conclusions of Unger. A 

 growing pot plant (geranium) in a thrifty condition was experi- 

 mented with. The whole of the pot was covered with a double 

 layer of oiled silk, and the free portion accurately adjusted 

 around the base of the stem, on which it was tied with elastic 

 cord. Thus prepared, no evaporation could take place from the 

 soil in the pot, and what is of more importance still, no moisture 

 could be thus supplied to the roots excepting that which was 

 contained in the soil in the pot. The plant was now placed under 

 a glass case which was situated over a shallow box in which there 

 was about four inches of soil which was kept saturated so that 

 the evaporation from it kept the air of the glass chamber quite 

 moist. The whole arrangement was placed near a window with 

 a southern exposure, the plant catching the rays of the sun for 

 about five hours of the day in clear weather. In this situation 

 the plant remained quiescent or dormant so far as any visible 

 growth or development was concerned, for about two weeks, 

 when it began to look languid and the margins of the leaves be- 

 gan to change in color and to show slight signs of foiling nutrition. 

 The explanation of this apparently long state of hybernation in 

 the plant is simple. The air in the case being too moist to allow 

 of scarce any transpiration, the plant retained the moisture in the 

 pot for purposes of nutrition only, and since the plant most prob- 

 ably grew but little during that period, there was quite sufficient 

 water in the pot for its uses for so long a time. At the end of the 

 two weeks the plant was taken out of the glass case and placed 

 in a sick chamber with the same exposure, in which three dozen 

 other thrifty plants were situated. The oil silk was allowed to 

 remain on and no water was supplied to the roots of the plant. 

 The atmosphere of the chamber was noticeably moist to the 

 senses, though agreeable. Here the sun's rays had an opportu- 

 nity of exciting the plant to transpire actively, and, as a conse- 

 quence, in a few days nutritive change became very decided, 

 leaf after leaf drying until at the end of another fortnight only a 

 couple much withered leaves were left on the plant. 



Now this experiment is not sufficiently conclusive to assure us 

 that absorption of moisture by the leaves is impossible ; but it 

 certainly must show to the satisfaction of every one that not 

 sufficient water can be taken in through them to carry on the 

 normal functions of the plant, and renders it extremely probable 

 the only source of moisture to the plants is through the roots. 



