SUGGESTIONS FOR RELIABLE HYPOTHESES 17i 



There are plants and animals which, precisely in the 

 same habitat, or in the same region, often produce 

 spontaneous deviations i.e. without a recognizable 

 external cause. Such bad ' species from the beginning 

 constituted the cross of the systematist who desired 

 to give a name to each form and thus ' pulverized/ 

 as Deperet puts it, the animal species concerned, 

 so that eventually nearly every individual bore a 

 special name. Among the plants there belongs to this 

 category the Evening Primrose (GEnothera Lamarckiana), 

 the Blackberry, the Hawkweed, and others ; among 

 the animals the Vine Snail (Helix striata), and some 

 Mussels (particularly Unio), are the most notoriously 

 ' bad ' species. 



These transformations, however, do not go so far 

 that the connection with a common ' basal form ' 

 cannot at once be recognized. More extended and more 

 constant transformations established in organisms 

 arise, however, when an animal or plant form occurs 

 in a definite, well-separated (isolated) region with 

 peculiar environment. Then the so-called local races 

 and local species are formed, which, by the exclusion 

 of free crossing with new blood and through long- 

 continued isolation, assume forms which can then only 

 be classed in the same genus, sometimes indeed only 

 in the same family, as their original ancestors. 



We will now treat more in detail those facts from 

 animal and plant geography of the present organisms 

 in connection with which the influence of the strictest 

 separation, and the in-breeding connected therewith 



