FACTS 237 



presently see how difficult it is to come to an agreement 

 as to the definition of species. 



On the other hand, the chances of amphimixis or fecund- 

 ation are so great that, out of a number as large as you 

 please of children coming from the same couple, there are 

 never two identical. What is there astonishing in the 

 fact that, out of the thousands of discontinuities separating 

 the individuals coming from a sowing of seed, some should 

 be greater than others ? Such discontinuities should be 

 still more striking when they are accompanied by a differ- 

 ence in colloid state, like that which separates muscle from 

 nerve or, perhaps, the fern from the prothallus. It is 

 enough to suppose that the specific protoplasm of Oenothera 

 has a certain number of physical states equally stable to 

 conceive how, influenced by the chances of amphimixis, 

 certain plants are led to jump the steps which separate one 

 of these states from the neighbouring state. As A. Giard 

 has remarked in his Discourse at the St. Louis Exposition, 

 it is possible that the following is what has happened. The 

 protoplasms of the parents were grazing the step which 

 separates two stable physical states, without actually land- 

 ing at it. Then a chance variation due to amphimixis, with- 

 out being actually greater than others, acquired special mor- 

 phogenic importance by passing the bound which separated 

 the two states. 



Finally, yet another hypothesis is possible. More and 

 more frequently, particularly in the vegetable kingdom, 

 we find associations or symbioses between different species. 

 Lichens result from the association of seaweed and mush- 

 room ; orchids are complete only when, at the beginning 

 of their evolution, they are associated with mushrooms 

 of the genus Fusarium. Possibly in many other plants 

 there exist symbiotic microbes, too minute perhaps to 



