ProcecdingH of the Royal Iris/t Academy. 



amount of water absorbed or transpired by our various xeropliytic, 

 mesophytie, and hydropbytic plants, of the relative intensities of 

 photosyntbesis, respiration, &c., in sun and shade plants? Such 

 questions can be satisfactorily answered only ])y experiments mad(; 

 with the plants of the associations under their natural conditions of 

 environment ; and the establishment of a Desert Botanical Laboratory 

 by the Carnegie Institution in the United States of America (24) is 

 a step in advance towards the attainment of such knowledge. 

 Experimental work of this kind in the field has also been begun in 

 Sweden, where Hesselmann (25) has studied quantitatively and in situ 

 the intensity of photosynthesis, respiration, and transpiration in the 

 plants composing certain associations (Icifiingar), and lias obtained 

 interesting and important results. AVe notice, too, that AYoodhead, in 

 liis work, is making provision for experimental work in situ, by 

 erecting suitable huts for research work in the woodlands which he 

 is studying. 



As mentioned above, however, the present ])aper is almost entirely 

 confined to tlie descriptive ecological survey of the area in question, 

 the physiographical and other features of which we shall now proceed 

 to consider. 



litekltuee quoted in the introduction. 



1. Smith, IIobert : 



On the Study of Plant Associations. Natural Science, vol. xiv., 

 p. 109. 1899. 



2. Wakming, E. : 



Plantesamfund. Grundtrak af den okologiske Plantegeografie. 



Kjcibenhavn : Pliilipsens Eorlag. 1895. 

 Lehrbuch der okologischen Pflanzengeographie. Deutsche 



Ausgabe von Dr. E. Knoblauch. Berlin : Borntraeger. 



1896. 



Ditto. 2 Ausgabe. Bearbeitet von P. Graebner. 1902. 



3. ScHiMPKii, A. F. W. : 



Pflanzen-Geographie auf Pliysiologischer Grundlage. Jena : 

 Eischer. 1898. 



Plant Geography on a Physiological Basis. English Transla- 

 tion, by W. B. Fischer, revised edition by Groom and Balfour, 

 London: Henry Pro wde. 1904. 



