224 DYNAMICS OF LIVING MATTER 



day or two. The case of starfish eggs is possibly still more striking. 

 The egg of a starfish, Asterias Forbesii, is, as a rule, immature when 

 taken from the ovary, and maturates when put into sea water. Ver)-^ 

 often not all the eggs of a female undergo maturation in sea water, and 

 I have found that maturation can be inhibited by putting the eggs into 

 slightly acid sea water. It was found that the eggs which maturate 

 but are not caused to develop die in a few hours, while the eggs that are 

 caused to develop or the eggs which fail to maturate (or are prevented 

 from so doing) will not die, even if kept in the same dish of sea-water.* 

 The eggs which are allowed to maturate, but are not caused to develop, 

 die just as well in perfectly sterilized sea water, in which the eggs keep 

 free from putrefaction for months, as in normal sea water or in sea water 

 to which cultures of bacteria of putrefaction have been added. These 

 and other facts indicate that in the mature egg processes occur which 

 lead invariably to the death of the egg under circumstances under which 

 the fertilized egg invariably keeps alive. 



As far as the second problem of transformation is concerned, namely, 

 the transformation at desire of one species into another, conditions are 

 more favorable since De Vries has succeeded in actually observing the 

 transformation of one species into another. 



De Vries discovered in experiments which have been carried on since 

 1886 in the most painstaking and laborious way, that from the seeds of 

 a certain plant, (Enothera Lamarckiana, there arise always a very 

 small number of plants which differ from the mother plants in definite 

 characteristics. t "These plants are from the very first true to seed!" 

 De Vries thus discovered that new forms arise from (Enothera La- 

 marckiana, not by gradual variation, as Darwin and Wallace had as- 

 sumed, but by a sudden jump. As an instance, the origin of the species 

 (Enothera gigas from (Enothera Lamarckiana may be mentioned. It 

 originated in De Vries's culture of 1895 in a single specimen, and this 

 first specimen was, as soon as it flowered, fertilized with its own pollen. 

 The action of insects was absolutely excluded. The following spring 

 the pure seed was sown (1897). The several hundred plants which 

 thus originated all differed in the same way from (Enothera Lamarcki- 

 ana, resembUng the mother plant of (Enothera gigas. The species has 

 since remained constant. In the same sudden manner the other new 

 species of (Enothera originated from (Enothera Lamarckiana. To this 

 sudden, discontinuous form of evolution De Vries gave the term "muta- 

 tion." The observations of De Vries also explain the fact which Dar- 

 win's idea of gradual evolution failed to explain ; namely, that species 

 can and usually do remain constant for thousands of years. The plants 



* Loeb, Pflugers Archiv, Vol. 93, p. 59, 1902. 



t Hugo de Vries, Die Mutationstheorie, Leipzig, 1901. 



