394 CARNEGIE INSTITUTION OF WASHINGTON. 



when grown in this water. The effect of this swamp water is marked 

 in the case of the palmetto, Sabal glabra, as in the sunflower, in spite 

 of the fact that transpiration studies indicate that it is a true xero- 

 phyte. The average rate of water-loss for 24 hours in tap-water was 

 about 1/35 as great for the palmetto as for the sunflower, while it was 

 more than twice as great for Scirpus and 3 to 5 times as great for Typha 

 as for sunflower. 



Photosynthetic Efficiency, by F. E. Clements and Frances Long. 



While determinations of the photosynthate present in killed leaves 

 have shown a general correspondence with light intensity, especially 

 in the case of ecads, it has become desirable to check this method by the 

 direct measurement of photosynthesis in the field. This not only 

 makes possible much greater accuracy, but it also permits detailed 

 measurement of the process throughout the day and for periods of 

 any length. In addition, it affords the opportunity of comparing the 

 course of photosynthesis with that of transpiration and respiration 

 and of determining their mutual relations. As a consequence, atten- 

 tion has been given primarily to the problem of devising and improv- 

 ing a portable field apparatus. This has resolved itself into the need 

 for compactness and for a practicable device for drav/ing a current of 

 air through the container. The former has been met by the use of a 

 celluloid chamber, which has the transparence of glass but is much 

 lighter and less subject to injury. The latter bids fair to be best 

 solved by the use of a fan driven by clock-work, since aspirators of 

 various types are much less convenient in the field. Moreover, for 

 ecological studies it is imperative to make use of the entire plant, and 

 this demands a larger amount of CO2 than in laboratory work with a 

 leaf or branch, especially when full sunlight is j)resent. 



Experimental Pollination, by F. E. Clements and Frances Long. 



In checking methods and results preliminary to publication, the four 

 major lines of study have received particular attention. These are 

 the life-history of the flower, normal pollination, experimental pollina- 

 tion, and competition for pollinators. The life-history from bud to 

 fruit has again been traced in about 50 species, and a score of the rep- 

 resentative types have been drawn in detail. Normal pollination has 

 again been studied in the more important flowers, and the habits of 

 the bees in particular have been checked by a study of their pollen- 

 masses. This confirms the result that many bees work exclusively 

 or nearly so on the preferred flower as long as it is abundant. Experi- 

 mental studies with mutilated flowers, crepe flowers, painted flowers, 

 added nectar, odor, etc., have been repeated with Aconitum, Del- 

 phinium, Epilobium, Gcraniuvi, Rosa, and Rubus. An endeavor has 

 been made to place these upon a quantitative basis. While the re- 

 sults with painted flowers, for example, seem contradictory, it is be- 



