Feb. '08] JOURNAL OF ECONOMIC ENTOMOLOGY 67 



any species (for later work see following paragraphs), and so far as 

 I am aware no one has yet traced the development of a disease organ- 

 ism within the body of a tick as has been so ably done in the some- 

 what analogous case of malarial organisms in Anopheles mosquitoes. 

 Also very little has been recorded in regard to the habits and meta- 

 morphoses of any species other than those of the genus Boophilus." 



Since 1905, however, several valuable contributions have been added, 

 including one upon the internal anatomy of Margaropus annulatus by 

 S. R. Williams* and by W. E. Allen.^ Mr. Nathan Banks of the Bu- 

 reau of Entomology now has in manuscript a revision of the ticks of 

 this country, which, when issued, will greatly aid in identification. 

 Koch" has elucidated much of the life cycle of Piroplasma higeminum, 

 the cause of splenetic or Texas fever, and has succeeded in discovering 

 the first stages of development of Piroplasma parvum, the parasite 

 of African Coast fever, which are undergone in the tick. Christ- 

 ophers,^ also Nuttall and Graham-Smith,^ have followed the complete 

 life cycle of Piroplasma canis, the cause of malignant jaundice of dogs. 



Doctors Smith and Kilborne,^ discovering in 1892 the role that the 

 cattle tick, Margaropus {= Boophilus) annulatus, plays in the trans- 

 mission of the protozoan, Piroplasma higeminum, the blood parasite 

 causing Texas fever of cattle in this country, paved the way for this 

 new field of investigation. Since that time a number of diseases of man 

 and the domestic animals have been found to be transmitted by these 

 parasites. Subsequent investigation has shown that ticks are the in- 

 termediate hosts of species belonging to the disease producing pro- 

 tozoan genus Piroplasma. It has also been shown that several diseases 

 produced by spirochaetge are transmitted by ticks. The conclusions 

 reached by Button and Todd^" are that some development of the spiro- 

 chaetEe of human tick fever takes place in the tick. Koch has found 

 the spirochaetae to multiply within the egg. Borrel and Marchoux^^ 

 have found the spirochaetee^ of fowls to develop at 35° C. in the body 

 of the tick. 



In order to show the zoological position of these blood parasites 

 (Piroplasma) transmitted by ticks, the following table taken partially 

 from Daniels and Stanton 's^^ most excellent work, is given: 



t>There Is still a difference of opinion as to the structure and relations of 

 the spirilla and spirochaetae. They have many similar characters but differ 

 (according to some authors), the latter having flagellse, which place them 

 across the imaginary line from the former into the protozoa, thus being con- 

 sidered as animal life, while the spirilla are bacteria (or lovs^ly organized 

 plants.) Dr. Raphael Blanchard in the Revue Veterinaire, 1906, p. 86, places 

 all that are pathogenic in the genus Spirochaeta. 



