96 B- LYNGE. 



when a rich man prepares a fine collection and presents it to 

 his friends, or a museum prepares a similar collection for ex- 

 change, or a poor specialist prepares one for sale, the collection 

 is in any case the same, and it cannot be said that if issued in 

 the first way it is not "Lichenes exsiccati", hut if in the last 

 manner it is. 



The labels are even more essential, since they should give 

 a guarantee that corresponding numbers of different sets really 

 are identical. It is therefore agreed that all labels should be 

 printed, or at least manifolded (not written). Any collection issued 

 later than the year 1905 should never be recognised as "Liche- 

 nes exsiccati" if this requirement is not fulfilled, but in the case 

 of earlier editors a too rigid application of this requirement 

 might lead to injustice, 



My index is primarily intended as a book of practical use 

 to colleagues, and when in doubt I have preferred to include a 

 collection rather than omit it, since the former proceeding is of 

 value to some scientists and harms none. 



A collection of "Lichenes exsiccati" would fail to achieve 

 its purpose, if we were not quite sure that the numbers of every 

 set were identical. It is essential that all the specimens of the 

 same Lichen should be collected from the same locality. Were 

 some specimens collected in Scandinavia and other specimens 

 of the same number (species) in the Mediterranean countries, the 

 collection would be quite useless as "Lichenes exsiccati", how- 

 ever valuable it might be as a separate collection. An editor 

 may succeed in procuring the same form from different localities, 

 but he can never be quite sure, and later generations would have 

 to form their own opinion as to the value of such collections. 

 The earlier scientists were not always aware of this fact, but 

 that is of course beyond my control. 



I shall endeavour to make my index an index of collec- 

 tions that have been issued in more than one set, (irrespective 

 of the method), with printed or manifolded labels or — in the case 



