392 TROPICAL WILD LIFE IN BRITISH GUIANA 



is commandeered by nature. She must be fitted to meet new 

 conditions in order to perpetuate her race. Thus the task 

 devolves upon Histolysis the wrecker and Histogenesis the 

 builder. 



During the period of larval growth, from the time it 

 hatches until the provisions in the cell are entirely consumed, 

 the grub rids itself of no waste matter whatever. Unlike 

 the larva of the butterfly that excretes every few minutes 

 as it eats during the days of its worm life, the young wasp 

 waits until its stores are gone and its cocoon spun before 

 passing off the waste of its five-day gorge. Even then it 

 waits another day for the event, finally depositing it in a 

 single mass at the lower pole of the cocoon. A few days 

 later pupation takes place. 



In the days which pass, between excretion and pupa- 

 tion, no foreign matter appears within the cocoon. The 

 insect is motionless ; its cradle, save for the hardened mass at 

 one end is scrupulously clean. I remove this mass, float it 

 out in a little water and subject it to a thorough inspection 

 under the microscope. It contains bits of chitin, hairs and 

 fragments of claws, all however, fragments of the deceased 

 roaches. There is nothing unusual in the array, no bits of 

 larval anatomy, no fragments of the grub itself. What then 

 becomes of the material that Histolysis is supposed to dis- 

 poil? Are the skin cells all of the grub's anatomy that serve 

 to build the wasp? 



I cut open the body of a grub, three days after the co- 

 coon is spun. The greater part of it runs through the inci- 

 sion as a smooth, pasty liquid amorphous in every way. At 

 eight days, I open a second grub. Now it is partly paste, 

 but mostly wasp ! 



The laborers of Histolysis are not altogether wreckers 

 then. They are concerned more with tearing down the old 

 timbers, removing the rusty nails, puttying the holes and 

 handing them back to the equally skillful employees of His- 



