July 28, 1893. J 



SCIENCE. 



51 



the supposed ancestors of the Artiodactyles from the Puerco 

 (Protogonodon and perhaps other genera, as suggested by Pro- 

 fessor Scott) the characters of the dentition are well differenti- 

 a'ed from those leading to the Perissodacljles. I have referred 

 upper teeth in the American Museum collection to Protogonodon, 

 which are of the tritubercular type, with exceedingly brachydont 

 crowns. These upper teeth differ considerably from those of the 

 bunodont Creodonta. The internal cones and intermediate tu- 

 bercles in Protogonodon have coalesced and nearly form ores- 

 cents The external cusps of these superior molars are depressed 

 and not as conical in section as in the Puerco Creodonta. The 

 lower true molars of Protogonodon are sexitubercular, but differ 

 in form from those of most of the Creodonta by the fact that the 

 anterior portion of the tooth (trigonid) is not raised above the 

 posterior (talon). The cusps of the lower true molars, as in the 

 case with those of the upper molars, coalesce and form continu- 

 ous tracts of worn enamel ; this applies particularly to the poste- 

 rior limb of each crescent. Lastly, the upper premolars in Pro- 

 togonodon are not yet known, but the lower teeth of this series 

 are well preserved and shows them to be absolutely simple in 

 structure, consisting of a cone with slightly enlarged heels. In 

 some specimens there is a trace of an internal cusp on the last 

 lower premolar. 



The characters above adduced as pertaining to the dentition of 

 Protogonodon approach closely those of the earliest known Amer- 

 ican Arliodactjle, viz.. Pantolestes from the Wasatch Eocene, I 

 would suggest accordingly that Pi'otogonodon may stand in an- 

 cestral relationship to this genus. 



I do not agree with Dr. Sclilosser in deriving the Artiodactyles 

 from any of the known Periptychidse, as the latter group has 

 been de6ned by Professor Cope. In nearly all of the Peripty- 

 cliidce the premolars are highly specialized and are not adapted 

 for further evolution. Professor Scott, in his very valuable paper 

 on the " Creodonta," only recently published, has subdivided the 

 genus Mioclaenus Cope into several new genera, limiting the lat- 

 ter genus for a few species only; the type being the ^Tioclaeniis 

 turgidus. The structures of the premolars in Mioclaenus are more 

 like those of some of the Periptychidas than the Creodonta, and 

 consequently Professor Scott believes that Mioclaenus is a condy- 

 larth. Other than the genera already mentioned as probably 

 having been persistent types, I would intimate that Mioclaenus 

 turgidus may stand in ancesiral relationship to some of the 

 White River bunodont Artiodactyles (Leptoe/icerits). The follow- 

 ing phylogenetio scheme may ilhi-trate the afSnities pi'oposed in 

 this paper: 

 Perlssodaclyla. Baaodoat Artlodactyla. Selenodont Artlodactyla. Amblypods. 



Buprotogonla. 



Protogonodon. Fantolambda. 



DO THE LEAVES OF OUR ORDINARY LAND PLANTS 

 ABSORB WATER? 



BY EDWARD A. BURT, EAST GALWAT, N.T. 



Conflicting answers have been given to this question. Hales, 

 BoussiBgault, and Henslow concluded from their experiments 

 that leaves do absorb water; other investigators have failed to 

 obtain such positive results, and have been inclined to doubt ab- 

 sorption. Furthermore, the theory that the transfer of liquids is 

 largely accomplished through dififerences in density of the liquids in 

 the plant caused and maintained by transpiration from the leaves — 

 this, by giving a sufficient function to the leaves, has probably de- 

 terred investigators from entering upon an inquiry that promised 

 only negative results, and that was beset with difficulties in carry- 

 ing out. Yet a moment's reflection shows us that during the growing 

 season of several months in each year, our vegetation is covered 

 with dew night after night, and often when periods of drought 

 prevent the plants from receiving an adequate supply of water 

 through their roots. Does it not seem probable that plants are 

 able to use the dew which covers their leaves? 



Under the direction of Professor Goodale and Mr. W. F. Ganong, 

 the writer has been recently carrying on a series of experiments 

 in the botanical laboratories of Harvard University to determine — 



(a) Whether it is probable that leaves do absorb water. 



(6) Whether the conditions under which such absorption occurs, 

 if it does occur, will not afford suitable ground for more special 

 investigation later on. 



Some of the results already reached seem to justify a prelim- 

 inary publication. 



Can Leaves Absorb Water ? 

 - To decide this, young branches of Diervilla grandiflora, com- 

 mon house geranium (Pelargonium), and Mesembryanthemum 

 were cut from the parent plants while in full leaf. The clean-cut 

 ends of these small branches were then dipped into a waterproof 

 varnish — Brunswick black — so as to completely cover the cut 

 ends and the sides for an eighth of an inch up the stem. The 

 branches were then allowed to lie on a table in the laboratory — 

 temperature, 70° F. — for a time until wilting occurred. They 

 were then weighed, sprinkled with water, and shut in a botanist's 

 tin collecting-box for from 16 to46 hours. Having recovered their 

 original fresh condition, the branches were then removed from 

 the box and dried carefully from adhering water by exposure to 

 the air of the room and by the use of blotting paper. They were 

 then weighed. In each case there was an increase in weight indi- 

 cative of absorption. The details are given in the following 

 table: — 



Henslow obtained absorption with cut branches in a large 

 number of cases and under a variety of conditions; but as he did 

 not cover the cut ends of his branches, it has been objected that 

 the absorption in his experiments occurred through the cut ends 

 rather than through the leaves. My experiments show that the 

 objection was not well taken. We must conclude that slightly 

 wilted leaves may absorb water. 



Do Leaves of Rooted Plants Absorb Water? 



Small vigorous-growing plants of Ricinus and of a small- 

 leaved Begonia were used. They were obtained from the green- 

 house in 3- and 3-inch pots. The pot and the lower portion of the 

 stem of each plant were then inclosed in a covering of sheet 

 rubber in the following manner: A small circular opening of less 

 than half an inch in diameter was cut in the centre of a piece of 

 sheet rubber of suitable size. The rubber was then stretched in 

 the region of the opening so as to make the aperture temporarily 

 larger. The pot was then slipped down through this opening. 



Upon lessening the tension, the rubber contracted clasping the 

 stem just below the lowest leaves. With a stout thread the rub- 

 ber was then wound firmly against the stem for a sufficient dis- 

 tance to make a close contact of the two. With its centre 

 suspended from the place where tied about the stem, the rubber 

 now hung down covering the pot loosely and completely conceal- 

 ing it. The lower portions of the rubber were now gathered 

 together underneath the pot and firmly tied together with strong 

 cord. 



A thrifty young begonia plant with its pot so covered had its 

 leaves thoroughly sprayed with water by means ot an atomizer 

 at 6 P.M. It was then placed under a large bell-jar in an atmo- 

 sphere made and kept damp by wetting the inner surface of the 

 jar with water and by suspending in the jar two large sponges 

 dripping wet. With its leaves wet, the plant was kept in this 

 damp atmosphere in the dark during the night. In the morning 

 it was removed from under the bell-jar, dried carefully, and then 

 weighed at 8.40 a.m. It had increased its weight 0.09 grams 



