PRODUCTION OF NEW SPECIE;S. 



293 



At the time the foregoing experiment was started another one was begun 

 in which the sexes matured their germ cells under the conditions of experi- 

 ment, but copulation and fertilization took place under normal conditions. 

 In the experiment 6 females were kept during the development of the first lot 

 of ova in normal condition and bred to normal males. During the develop- 

 ment of the second, third, and fourth batches they were kept under the condi- 

 tions of experiment, and bred to males whose germ cells had been developed 

 under the conditions of experiment, while the fifth and sixth lots were devel- 

 oped under normal conditions and fertilized by normal males. The three 

 lots of eggs obtained we shall call A, B, and C. The results from the lots 

 were rather interesting, and are given in diagrammatic form in text-figure 29. 



These two experiments with L. multitcsniata show that when the imagines 

 are subjected to strong stimuli during the development of the germ cells the 

 result is the production of a large number of rapidly developing extreme and 



.GENERATIONS, 



III 



IV 



V 



VI 



MULTIT/ENIATA 



82^, I 110^ CFrom Guadalupe, D. F., Mexico, 1903. 



MULTIT/ENIATA 

 [61 J",^! 66 9^ (Eeared at Chicago, September and October, 1903. 



^ ^'s 6 c?' 

 X Y 



germ cells germ cells 

 not stimulated 



stimulated 



MULTIT/ENIATA 

 20<J, I 239 



MULTIT/ENIATA 



2^$, I 149 



MULTIT/ENIATA 

 12<?, I 99 



MULTIT/£NIATA 



? 



Ova developed under 

 normal conditions, 

 crossed with males 

 of X 



Ova developed under 

 changed conditions, 

 crossed with males 

 of Y 



MULTIT/ENIATA 

 6^, I 79 



MULTIT/ENIATA 

 19^, I 339 



MULTIT/ENIATA 

 11^, 1129 - 



MULTIT/ENIATA 



7 

 All killed in late larval and pupal stages. 



Text-figure 29. 



MELANOTHORAX 

 19^, [249 



MELANOTHORAX 

 J 20^, 1309 



MELANOTHORAX 

 8c?, [69 



MELANOTHORAX 

 7 



RUBICUNDA 

 6<?, ] 109 



RUBICUNDA 



10^,1 119 



RUBICUNDA 

 14^,1 179 



RUBICUNDA 

 7 



Ova developed under 

 normal conditions, 

 crossed with males 

 of X 



<r 

 219 eggs 



IviULTIT/ENIATA 



10^, I 219 



MULTIT,€NIATA 

 16J, I 189 



MULTIT/ENIATA 

 4<?, I 59,^ 



MULTIT/ENIATA 



? 



permanent modifications. There is a rapid transformation of the characters 

 of the stimulated germs into new arrangements, giving us new characteristics 

 and incipient species. The first series of cultures are in all respects like those 

 given for decemlineata — that is, parent beetles reared under the condition of 

 the experiment gave a higher percentage of offspring with modification of 

 permanency. The second experiment, however, shows clearly that it is only 

 those germ cells that are acted upon during growth and maturation that are 

 changed, and that, although others are present as primitive germ cells in the 

 body of the parent, they do not seem to be modified unless they, too, are sub- 

 jected to stimuli in the growth periods ; that is, it is in the growth period, 



