644 D. B. CASTEEL 



skilold ('07), Bonnet ('07) and Samson ('09) as indicated in the 

 latter portion of this paper. All of these investigators are con- 

 cerned more particularly with the metamorphosis of the sperma- 

 tozoon from the spermatid, and they give but brief and incom- 

 plete accounts of the preceding stages. 



My attention was attracted to the growing spermatocytes and 

 the spermatids of Argas by their relatively large size and the 

 prominence of their cytoplasmic inclusions. This account repre- 

 sents the results of a work undertaken in the hope that a thor- 

 ough study of these bodies throughout the history of the male 

 germ cells might add to our knowledge of those problematical 

 structures, the mitochondria, and that our data upon the sper- 

 miohistiogenesis of the Acarines might be enlarged. For the 

 sake of conciseness and to avoid needless repetition in the litera- 

 ture, reference is limited to papers which bear very directly 

 upon the subject and no general review or discussion of cyto- 

 plasmic inclusions is attempted. Comprehensive reviews may 

 be found in the works of Benda (1899, '03), Meves ('08, '10 

 et al.), Faure-Fremiet ('10), Duesberg ('11), Hegner ('14), 

 Cowdry ('12, '16) and others. 



During the progress of my work the germ cells of several 

 species of ticks have been examined for comparison. I am 

 indebted to Air. F. C. Bishopp of the United States Department 

 of Agriculture for material of this nature sent to me from the 

 Dallas Laboratory. I also wish to express my appreciation of 

 the facilities afforded me during the summer of 1915 by Prof. 

 F. R. Lillie at the Marine Biological Laboratory at Woods Hole. 

 I am particularly indebted to Dr. E. V. Cowdry for certain vital 

 stains and for helpful suggestions regarding technique and 

 interpretation. 



MATERIAL AND METHODS 



The chicken-tick, fowl-tick or blue-bug, Argas miniatus (Koch), 

 is a common parasite of fowls in the southwestern portion of 

 the United States. It is synonymous with Argas persicus which 

 is found in many parts of the world, in tropical and subtropical 

 regions. The adult ticks are readily obtained from an infested 



