ARE THESE CHANGES IN FORM PERMANENT? 513 



individual more resistant, support and protect its organs, and render it possible 

 for the separate parts to perform their work in spite of the necessarily altered 

 conditions. They seem to have the task of keeping the plant alive under very 

 different vital conditions, of promoting growth and the formation of offshoots 

 and fruit with the smallest possible expenditure, and they may therefore be 

 regarded as adaptations to the particular conditions of soil and climate. 



The capacity for adaptation is of course founded in the specific constitution of 

 the protoplasm, and is very different in different species. One species may adapt 

 itself by appropriate alterations to the influence of bright light, submersion under 

 water, a dry atmosphere, &c., while another cannot do so. If the protoplasm of the 

 Flax {Linum usitatissimitm) could manufacture as much anthocyanin in its green 

 tissue as the Summer Savory (Satureja hortensis) it would blossom and ripen its 

 fruits in alpine regions as this plant does, and would not succumb to the effect of 

 the strong light. If the protoplasm of the Common Bent-grass (Agrostis vulgaris) 

 were able to continue its constructive activity under water it would not perish as 

 soon as it is submerged, but would maintain itself like the stoloniferous species 

 (Agrostis stolonifera) by green stalks and leaves adapted to an aquatic habitat. 

 In short, the adaptability of each species is restricted within definite limits which 

 depend upon the specific constitution of the protoplasm and cannot be overstepped. 



It is a matter of great import in the history of species whether modifications 



in form effected by change of soil and climate are transmitted to the descendants, 



and whether they can be inherited. This of course can only be ascertained by 



experiments, and by experiments in which all possible sources of error have been 



eliminated. This last remark is made advisedly, for the sources of error in such 



experiments are very numerous. I will briefly indicate two which interfered with 



some experiments I carried out in the years 1863 and 1864. It is not enough to 



be careful that the seeds sown in the prepared experimental beds are all from the 



same plant; care must also be taken to see that they are not the result of a hj^brid 



cross-fertilization. Some seeds taken in 1863 from a plant of Dianthus alpinus 



growing in the Botanic Garden at Innsbruck, and sown in different soil in two 



experimental beds, produced plants in soil free from lime, which, in their external 



appearance, agreed with Dianthus deltoides. It seemed as if Dianthus alpinus, a 



lover of limestone rock, had become transformed into Dianthtis deltoides when 



grown without lime. The seeds of the plant so like Dianthus deltoides were again 



sown in soil without lime, but the resulting plants no longer resembled this species; 



they showed themselves to be constant in their characteristics. The whole 



experiment with Dianthus alpinus was then repeated, but this time the plants 



on the clay soil without lime did not change, and I was obliged to conclude that 



the plant I had regarded as a stage in the transformation of Dianthus alpinus 



into Dianthus deltoides was a hybrid of these two species. In order to be certain 



about this a crossing between the two species was effected artificially. From the 



resulting seed plants were actually grown which were exactly like those I had 



regarded as transformations, and there was no longer any doubt that some of the 

 Vol. II. 83 



