342 CARNEGIE INSTITUTION OF WASHINGTON. 



the pressure of one atmosphere, when the normal movements take place. 

 With Oenothera ccespitosa a temperature of 25° C kept flowers closed for 1 to 

 2 hours after normal opening had occurred outside, while the removal of the 

 bell-jar caused them to begin opening at once and to reach full expansion in 

 about an hour. Lowering the temperature 10° to 12° from 2 until 6 o'clock 

 maintained closure after normal opening had begun. It is planned to con- 

 tinue the investigation until several examples of the various types of hemer- 

 anthous, n3^ctanthous, and ephemeral flowers and heads have been passed in 

 review. 



Correlation in Bud Development, by F. E. Clements. 



In the course of a comprehensive study of the movement of food within 

 the plant, an earlier experimental series in bud development has been resumed 

 and continued during the past 3 years. This has dealt chiefly with Melia 

 and Populus, but Fraxinus, Salix, Prunus, and Morus have also been taken 

 into account, and it is expected to extend the investigation to include the 

 major types of buds, including herbaceous ones. In addition to extensive 

 observations of the normal behavior of shoots and sprouts in various positions, 

 the following experimental methods have been employed: (1) change of 

 position of shoot, both before and after the opening of buds; (2) transfer of 

 shoots to water, nutrient, and food solutions; (3) removal of buds from the 

 shoot in varying manner and position; (4) supplying sugars, water, etc., to 

 individual buds or shoots; (5) wounding. While there was some variation in 

 behavior, both observation and experiment showed that change of position 

 to the horizontal or inverted was practically without effect upon the order of 

 bud development in both leaf and flower buds. Furthermore, it was possible 

 to develop any bud of a shoot by removing all the buds above or below it as 

 the type of twig demanded, though this was less successful with flower buds, 

 owing to their rapid expansion. For the addition of glucose a 2-inch section of 

 thick-walled glass tubing was drawn out to a short point, which could be 

 easily forced into the shoot, and this was filled with a 1 per cent solution of 

 glucose and stoppered with a cotton plug. Checks were secured by employing 

 similar tubes filled with water, as well as empty ones, to determine the effect 

 of wounding alone. Each glucose tube was inserted a short distance above 

 or below the bud to be forced, and the biids selected were largely those destined 

 to remain dormant at the base of the twig in the ordinary course of develop- 

 ment. In all cases the buds fed with glucose opened and the leaves expanded 

 from 1 to 2 weeks earlier than those in the upper portion of the shoot, the rate 

 of growth depending clearly upon the amount of sugar supplied. The evidence 

 from all three sources, namely, change of position, removal of buds, and feeding 

 with glucose, shows that development depended on the course taken by the 

 food-laden sap in response to the competition for it. For the species employed 

 the proof was conclusively against the hypothesis of an inhibiting substance 

 that suppresses lower buds in consequence of the effect of gravitj'- upon it. 



Experimental Taxonomy, by F. E. Clements, H. M. Hall, and I. M. Johnston. 

 Transplant activities were greatly extended in California during the year. 

 For this purpose a transect was selected which extends from the coast of San 

 Mateo County across the interior valley and the Sierra Nevada to the sage- 

 brush desert of Mono County. On this section practically all conditions and 

 communities are to be found — from alpine to coastal on the one hand and to 



