342 



C. SKOTTSBERG 



The fact that Irmsciikr tried to prove that the distribution of plants strongly 

 su|:)ports \\'K(;fnkr's hypothesis does not lessen the value of what he says about 

 the limited capacity of plants to migrate. It is small in the flowering plants [14.3. 291): 



Dass bei den Hliitenptlanzen die J^eforderung der Samen und Friichte durch Wind, 

 Wasser und I'iere ganz wescntlich eingeschrankt werden muss und fiir geschlossene 

 i-'orniationen auf grossen Kntfernungen hin nicht in Frage kommt, ist heute von den 

 rtlan/.engeograi)hcn allgeniein anerkannt. 



Irmsciikr is too optimistic, we have seen that there are phytogeographers 

 to whom overseas migration is not only possible and undoubtedly happens, on 

 rare occasions at least, but rather of quite common occurrence. And with regard 

 to s{)ore-plants their distribution should, if this be correct, show quite different 

 distribution patterns than they actually do. The bryophytes are no exception to 

 the rule. iRMSCiil'.R remarks that already in 1903 SlEPllANl denied that liverworts 

 are able to make long and successful jumps. Attention should be paid to Domin's 

 valuable j)aper [yd] in which he brings together numerous facts illustrating the same 

 definite distribution patterns in this as in other groups, and Miss FULFORl) (e.g. 

 10 ;] has arrived at the same conclusion. We know that the spores, in many cases 

 at least, are extremely sensitive to changed conditions and lose their viability 

 very ra[)idly when exposed to the air — a promising field for experiments. Regard- 

 ing mosses I refer to Herzog's work [i2g) where he speaks against the belief in 

 the importance and great range of dispersal through the air. We find, IRMSCIIER 

 says, the same disjunctions, the same part areas (Teilareale) in angiosperms, 

 gymnosperms, ferns and bryophytes, and he continues p. 292 : 



Dass diese vier in ihren Verbreitungsmitteln so verschiedenen Pflanzengruppen die- 

 seli)cn \'erhrcitungszuge ihrer Disjunktelemente ergeben, zeigt wohl einwandfrei, dass 

 hierfur der "Wind" ebenso wie andere iiussere Krafte als Ursache abzulehnen sind. 

 Wiiren sic in aiisschlaggcbender Weise an der Ausbreitung beteiligt, miisste die Besie- 

 dclung entsj)rechend der Verschiedenheit der Friichte, Samen und Sporen ebenso ver- 

 schiedcnartig ausgetallen scin, d. h. in den einzelnen Gruppen dieser biologischen Ver- 

 schiedenheit entsprcchcnde charakteristische Merkmale zeigen. Dies ist aber nicht der 

 i''all. Der alien vicr druppen ge m e i n sam en hochdisjunkten Ausbildung so vieler Areale 

 nuiss vichnehr cine andere Ursache zu (irunde liegcn . . . 



This conniion cause was, in Irmsciier's opinion, continental displacement in the 

 sense of Wi;(;ener. Those who disagree with him will have to look for vertical 

 movements, emergence and submergence of land. 



Lichens, fungi etc. were not included in Irmsc:her's discussion. A survey of 

 their distribution patterns is something to be asked for. Lichens are said to de- 

 |)en(l on their vegetative reproduction bodies more than on spores. 



It is maintained that, with certain exceptions, terrestrial animals spread 

 less easily than plants. 1 have consulted a number of zoogeographers in order to 

 learn their opinion on the mode of transport likely to be used by invertebrates 

 in their sup[K)sed ocean voyages. Birds etc. are left aside here. 



Numerous insects, butterflies, moths, flies, hymenoptera, grashoppers, cock- 

 roaches, as well as spiders, myriapods, etc. follow man from land to land, from 

 island to island. This is, I daresay, the only safe way for such animals to get 



