igoo-i.] Effects of Water on Foliage Leaves. 261 



were extracted from leaves, and also that under certain conditions these 

 salts were resorbed, a series of experiments was arranged to test the 

 matter from another point of view. 



Guttation drops were produced upon the following plants : — 

 Tropaeolum, Maize, Tomato and Phaseolus. Five leaves of each were 

 then placed in a moist, atmosphere, and five of each in an atmosphere 

 whose humidity was very low. When the water of the guttation drops 

 had disappeared it was found, upon close examination, that a whitish 

 deposit lay where the larger drops were upon the leaves in the dry 

 atmosphere. Upon those lying in the moist chamber no deposit was 

 found. 



These drops contained, as shown by analysis, potassium carbonate, 

 calcium carbonate and some organic substances. This analysis is 

 corroborated in part by that of Nestler (1899) who states that he found 

 potassium carbonate in drops produced upon leaves of Phaseolus, and 

 on some of the Malvacecs. 



In order to determine whether a substance similar to that produced 

 by immersion could be extracted in a shorter time than that employed 

 in the foregoing experiments, a number of tests were made with growing 

 plants. Ten different species were taken and the leaves subjected to a 

 fine spray of distilled water for fifteen minutes. The water was then 

 carefully collected and slowly evaporated down to dryness. In six out 

 of the ten ca^es, a faint crystalline deposit was found upon evaporation. 

 In one case, that of Nicotiana, a very considerable amount was found. 

 This plant was one of those which showed with the distilled water, a 

 strong alkaline reaction in a short time. When the leaves of the other 

 three plants were tested as in the first series they also produced a 

 deposit after a short time. 



In regard to the calcareous incrustations found upon desert plants, 

 Volkens calls attention to the fact that they occur chiefly upon desert 

 plants which grow upon soil which was once the bottom of an inland 

 sea, and which, therefore, contains a considerable amount of lime. It 

 may be said that two things particularly contribute to their formation, — 

 abundance of material, and an atmosphere periodically moist and dry. 

 They are spread over the surfaces of leaves, according to Nestler, and 

 also Noll, by means of hairs and corrugations, leaving no indication as 

 to the place upon the leaf from which they came. The writer has noticed 

 leaves of plants, other than those producing incrustations, having peculiar 

 striations and trichomes which may function, as Nestler suggested, to 

 transport water or solutions over the surface of the leaf (Fig. 10). 

 3 



