FAMILY I. RICKETTSIACEAE 953 



B. Symbiotic to the point that special mycetomes are developed for harboring the 

 organisms, which are not pathogenic, in the host. 



Genus VII. Sytnbiotes, p. 956. 

 II. Filterable; cause blue disease of beetle larvae; associated with intracellular, crystalline 

 inclusions; reportedly invade cell nuclei. 



Genus VIII. Rtckettsiella, p. 957. 



Genus VI. Wolbachia Hertig, 1936. 

 (Parasitology, 28, 1936, 472.) 



Wol.ba'chi.a. M.L. fem.n. Wolbachia named forS. B. Wolbach, who described the rickett- 

 sial agent of Rocky Mountain spotted fever. 



Microorganisms possessing the general characteristics of the rickettsiae and e.xhibiting 

 not only minute, bacterium-like forms appearing with dark-field illumination as luminous 

 rods and points but also enlarged forms within the body of which are contained one to 

 several smaller individuals. Pleomorphism is characteristic, and it is usually found in organ- 

 isms in an intracellular location; the few extracellular species, e.g. Wolbachia melophagi, 

 may eventually be regarded as not belonging to this genus. 



The tj-pe species is Wolbachia pipientis Hertig. 



Key to the species of genus Wolbachia. 



I. Found in insects. 



A. Found in mosquitoes. 



1. Found in the gonadal cells of mosquitoes, where degeneration occurs. 



1. Wolbachia pipientis. 



2. Found in the epithelial lining of the stomach of mosquitoes, where destruction of 

 the hind gut occurs. 



2. Wolbachia culicis. 



B. Not found in mosquitoes 

 1. Found in fleas. 



2. Found in lice. 



3. Wolbachia ctenocephali . 



4. Wolbachia pulex. 



5. Wolbachia trichodectae . 



6. Wolbachia linognathi. 



3. Found in the sheep ked; grows on non-living media (glucose-blood-bouillon-agar). 



7. Wolbachia melophagi. 

 II. Found in arachnids. 



A. Found in the Rocky Mountain wood tick. 



8. Wolbachia dermacentrophila. 



B. Found in mites. 



9. Wolbachia sericea. 



1. Wolbachia pipientis Hertig, 1936. diplococcoid forms are also observed. Ir- 



(Rickettsia of Culex pipiens, Hertig and regularity rather than symmetry is pro- 



Wolbach, Jour. Med. Res., 44, 1924, 329; nounced. The larger coccoid forms may 



Hertig, Parasitology, 28, 1936, 453.) measure up to 1.8 microns in diameter. 



pi.pi.en'tis. M.L. pipiens specific epithet Stain well with Giemsa's stain but poorly 



of the host mosquito, Culex pipiens; M.L. with aniline dyes. 



gen. noun pipientis oi pipiens. Cultivation: Attempts to cultivate this 



Small, coccoid forms measure 0.25 to 0.5 organism in cell-free media have been un- 



micron in diameter, and the rods measure successful; attempts in embryonated 



0.25 to 0.5 by 0.5 to 1.3 microns. Paired and chicken eggs are unreported. 



