1907.] Wheeler, The Polymorphism of Ants. 21 



in the larva and cannot be accurately controlled by the worker ants. The 

 theoretical bearings of these considerations will be postponed to a subse- 

 quent portion of this article. 



Two years later (June 21, 1903), on revisiting New Braunfels I found 

 on the very same hill slope two more colonies of Ph. comviutata containing 

 mermithergates. On this occasion every effort was made to secure the 

 entire personnel of the colonies in a living condition. One colony, confined 

 in too small a bottle, died before I reached my home, the other was success- 

 fully transferred to an artificial nest. On examining the .asphyxiated colony 

 I found it to consist of many female larvte and pupae, a few soldier and sev- 

 eral worker larvae and pupae, and a dozen mermithergates which varied con- 

 siderably in size from individuals but little larger than the workers and 

 without ocelli, to huge individuals like those taken two years previously. 

 These large mermithergates possessed ocelli, a thoracic structure like the 

 soldiers and a rich red color like the females. Three pupal mermither- 

 gates were also found but their gasters were not distended. The earth of 

 the nest contained two free Merm,ithes. 



The personnel of the living colony comprised six adult and three pupal 

 mermithergates, a winged and several pupal females, and a number of larval, 

 pupal and adult workers and soldiers. All of the pupal mermithergates, 

 like those in the asphyxiated colony, had the gaster in proper proportion to 

 the remainder of the body, so that they appeared to be merely gigantic 

 worker pupae. One of these hatched June 24, the two others July 2. As 

 soon as they had hatched, their gasters began to enlarge rapidly and in the 

 course of a few days the coils of the Merviis became visible through the 

 distended pellucid membranes between the widely separated segmental 

 sclerites. Evidently the parasites were present but of very small size in 

 the pupae and grew very rapidly during the callow stages of their hosts while 

 the chitinous investment of the gaster was still soft and distensible. This 

 sudden growth of the parasite is probably due to the rich and abundant food 

 with Avhich the recently hatched callow is supplied by her sister workers. 



This colony of Ph. commutatn was kept under observation till August 12. 

 Of the nine mermithergates which it contained, three had died by June 27, 

 and three more by July 19, while the nest was being transported in my hand 

 luggage from Texas to Colorado. Of the surviving three, two died July 

 25 and 30 and the last August 12. Hence, at least one of these parasitized 

 ants must have lived fully six weeks in the imaginal stage. In all of these 

 cases the Mermis died within its host and both were carried to the refuse 

 heap by the workers. One of the dead mermithergates had Ijurst and the 

 loops of the parasite protruded. In a state of nature it probably escapes 

 from its host at this or an earlier stage, and enters the soil for the purpose 



