— 160 — 



On the other hand the spectrum of Transcaspia agrees 

 in the main with the spectra for Samos, the Libyan desert, 

 Cyrenaica and Death Valley respectively. The point of maximum 

 intensity for all these spectra lies in the Therophytes. In the 

 hotter of these areas, the Libyan desert and Death Valley, 

 the Chamaephytes and the Fanerophytes are also prominent. 



As regards its biological spectrum, Transcaspia thus 

 presents the same type as the countries of the Mediter- 

 ranean, at least the eastern parts. We are further led to the 

 conclusion that parts at least of the western countries of the 

 Mediterranean should also be included here because 35 per 

 ct. Therophytes are found on the Iberian steppes (Willkomm 

 1894 p. 280). 



All these Therophyte- spectra are contingent upon the 

 same climate: winter-rains and a dry hot summer. This 

 forms a link in what is termed by Raunki^er a C-climate 

 series, i. e. a series starting at the Equator with a tropical 

 moist climate, its continuation northwards being determined 

 in this way, that although the heat de.creases so does the 

 precipitation at least as regards the summer. Thus we get 

 a dry climate characterised by a "Therophyte spectrum". 

 Still farther north the precipitation again increases, and we 

 have here a temperate Hemicryptophyte-climate which in 

 arctic countries is succeeded by a Chamaephyte-climate. Such 

 C-climate series are especially met with in the western parts 

 of large continents. Death Valley shows the unfavourable dry 

 climate in the series which runs through western America. 

 Transcaspia and the countries of the Mediterranean represent 

 the corresponding link in the series through the western parts 

 of the continents of the Old World. 



The B-Climate series passing through the eastern parts 

 of the continents, and which has a favourable precipitation 

 throughout does not come within the scope of this memoir. 



If on the other hand we compare the spectrum of 

 Transcaspia with those of Yekaterinoslaw and Pamir, we 

 arrive at the result that whether we proceed from Transcas- 

 pia northwards to the south Russian steppe, or upwards 

 into the mountains, the Therophytes decrease, while the 

 Hemicryptophytes increase in number. This is in accordance 



