94 Thiiiy-Fiyst Annual Meeting 



(lujji'ndent upon the soil and because they develop a large volume 

 of vegetation during the growing season. 



To recapitulate, we have first the facts hitherto known, that 

 the larger aquatics are important as furnishers of shelter, as 

 aerating agents, as a base of attachment for the growth of Algae 

 and as direct food for some animals. Second, the fact first 

 established in this pai)er, that these plants are important agents, 

 through which the soil is nuide to contribute a goodly share to 

 the food supjily of the lake. 



DISCUSSION OF DR. POXD's PAPER. 



Dr. Birge : Was the experiment tried of raising these plants 

 in boxes with earth and water, but with the roots removed ? In 

 the experiment described there was onl}'- one arrangement given 

 — })lants with roots and earth and plants without roots, — and 

 with the ordinary lake water, of course. If 6 inches of earth had 

 been placed in this box, it seems to me that a good deal of min- 

 eral salt might leach out of the earth, which the plants might 

 have absorbed through the leaves ; and I would ask, was that ex- 

 periment tried, to see the diiference. 



Prof. Ward : I was only an observer of the experiment, but 

 it is evident that in one respect, at least, the statement of the 

 author has not been clearly understood. The roots were not re- 

 moved from the plants, but the latter were very carefully select- 

 ed, so that there should l)e no chance of any kind of bruising or 

 breaking of the tissue to afford the slightest ground for suppos- 

 ing they were not in ^^erfect ])hysiological condition. The ex- 

 |icrinients were also tried in water so comparatively shalhiw that 

 while there miglit have been a difference under the conditions 

 wliich Dr. Birge mentions, I should rather imagine that tliere 

 would mil l)e. So far as I know, the exact experiment which he 

 indicates of placiug earth in tlie box liut not in contact with the 

 roots of the plant, was not ti-icd. It, however, may have been, 

 for I))-. Pond experimented very extensively and there were 

 many cxperinu'nts made of which he gave no definite report. 



Mr. .1. J. Siranahan, of Georgia: If the ]dant myriophyl- 

 luui were used in n jiond with poor soil and puiv soft water, what 

 would the result be ? 



I'rof. Ward : I wish Dr. Pond were here. He experimented 



