114 THE ALTERNATING GENERATIONS 



Whence it follows that the development of the species in 

 this case does not take place by means of several genera- 

 tions, but through several broods of the same generation. 

 The reason of the great number of ''feeders," and for 

 the common good of " workers ^^ so that they often con- 

 stitute thousands, whilst the fertile individuals scarcely 

 amount to hundreds* may be readily understood, when we 

 consider more closely the regular societies oiBees and Ants, 

 and witness the labour required for the nourishment of the 

 young. But on the other hand, how the development 

 of the species is promoted by the midtitude of " nursing" 

 animals {amme) of which we often see thousands for each 

 single fertile one, appears to us difficult of explanation, 

 since, even all of them can only be regarded as animated 

 organs, which do not appear to act for or with each other. 

 It does not, however, seem to me improbable, that even 

 the Aphides, trematode nurses, and other parasites, which 

 are so immediately injimous to the organisms in or upon 

 which they Hve, are not destined merely to promote the 

 extension of the species, but that they also induce in the 

 organisms themselves, conditions necessarily more and 

 more favorable to a later generation ; plants also and 

 animals afford us many instances, that to a certain abun- 

 dance of parasites there usually succeeds a complete over- 

 flow of them. 



I conclude with the remark, that, inasmuch as in the 

 system of " nursing," the whole advancement of the 

 welfare of the young is effected only by a still and 

 peaceful organic activity, is only a function of the vegeta- 

 tive life of the individual, so also all those forms of 

 animals in whose development the ''nursing' system 

 obtains, actually remind us of the propagation and vital 

 cycle of plants. For it is peculiar to plants and as it 

 were their special characteristic, that the germ, the pri- 

 mordial individual in the vegetation or seed, is competent 

 to produce individuals which are again capable of pro- 



* In a liivo of bees there are from 2000 to 3000 males, and only one 

 female to 50,000 " feeders" and "workers." 



