40 
Paul Jaccard. 
florulse shows that a great number of common species with a 
distribution through the entire chain of the Central Alps are 
actually absent over considerable stretches of country, while the 
conditions apparently capable of assuring their existence are every¬ 
where realised. 
We are thus led to ask whether the commonest species 
possess, like the rare species, a discontinuous distribution within 
the area of their occurrence. 
In order to try and find a solution of this problem, a com¬ 
parison was made, not of all the species of the districts W, T and 
D, but only of those constituting a single type of formation. For 
this purpose the alpine meadow above 1900 metres was chosen, 
and localities of equal area were selected, as closely similar as 
possible in respect of declivity, humidity and the general state 
of development of the flora. 
The following is a list of these localities, with exposure, nature 
of substratum, and number of species collected in each case. The 
areas, averaging 3 to 4 hectares (say 7 to 10 acres each), the 
slope (20—30°) and altitude (between 1900 and 2400 metres), 
differ very slightly in the different cases. 
Locality. 
Substratum. 
Expo¬ 
sure. 
Number 
of Species 
1. 
Plan la chaud, Val 
Calciferous Triassic. 
Ferret 
schists 
West 
101 
2. 
La Peulaz, Val 
Ferret 
East 
107 
3. 
South slope of Col 
Lower Jurassic (with 
South- 
Ferret 
quartzites) 
West 
106 
4. 
Alpes des Tsesse- 
taz, Combe de La, 
Entremont - 
Dolomite 
East 
99 
5. 
Alpages des Vingt- 
Calciferous Triassic 
Huit, Bagnes 
schists and Casana 
schists - 
West 
140 
6. 
Barberine, Trient 
Lower J urassic lime- 
South- 
stone 
West 
114 
7. 
Luisin, Emaney - 
Gneiss 
West 
173 
8. 
Gagnerie, Salanfe 
Upper Jurassic lime- 
stone 
West 
147 
9. 
Iffigen, Wildhorn 
Cretaceous & num- 
South- 
mulitic limestone 
East 
147 
10. 
Kuh-Dungel, Wild- 
North- 
horn 
>> J? 
East 
150 
