NAMES OF ASSISTANTS. 245 



with it, as well as for those relating to the specimens of elm, 

 were furnished by him. 



For the very convenient form of stopcocks used in the 

 mercurial gauges, we are indebted to the ingenuity of Prof. 

 S. H. Peabody. 



Much credit is due to Mr. D. P. Penhallow, a post-graduate 

 student, for his untiring devotion to the study of the squash- 

 vine, with which he spent many days and nights, observing 

 its mode of growth and making complete microscopical draw- 

 ings of all its structure. He also adjusted gauges to several 

 herbaceous plants, and reported upon the pressure of their 

 saps. He assisted in finding the per cent, of water in various 

 species of wood at different seasons of the year, and his 

 pencil prepared all the drawings, except those already men- 

 tioned. 



Charles Wellington, B.S., assistant in the chemical labor- 

 atory, has undertaken to determine the composition of various 

 saps and the effect on them of the advancing season. This 

 important investigation is not yet completed. 



Mr. Walter H. Knapp, with great fidelity, furnished the 

 material for the table showing the amount of sap which flowed 

 daily from each species. 



Mr. Atherton Clark made the observations on the water 

 gauges, except that on the sugar maple, on the mercurial 

 gauges in the case of the white birch root, the apple root and 

 the three on the grape vine, one of which . was thirty feet 

 from the ground. He also did much of the work relating 1 to 

 the time when each species begins to flow. 



Mr. William P. Brooks began and carried out very thor- 

 oughly a series of observations to learn precisely what species 

 flowed, at what time in the season, and how rapidly, visiting 

 for this purpose about forty species daily for several weeks. 

 In some unaccountable manner, the memorandum book con- 

 taining most of his records has been lost, and so his report is 

 incomplete. 



Mr. Henry Hague recorded the variations on the mercurial 

 gauges upon the four birches, one of them thirty feet from 

 the ground ; and on the hornbeam, three times daily for many 

 weeks. 



Mr. George R. Dodge attended to a series of experiments 



