662 D. B. CASTEEL 



Benda ('99), and more recently Duesberg ('10) has advanced the 

 idea that the myofibrils of striated muscle are of mitochondrial 

 origin. As has been noted, mitochondria are found only in the 

 end of the sperm-tube which shows active movement. 



Samson's ('09) accounts of the metamorphosis of the sperma- 

 tozoa of Ixodes ricinus and Ornithodoros moubata are in many 

 respects parallel to that of Argas as here related. Starting with 

 a very brief description of the spermatid of Ornithodoros (illus- 

 trated by two figures) she follows the formation of both inner 

 and outer tubes and notes the manner in which the nucleus 

 migrates along the outer surface of the outer tube. She also 

 notes, but does not represent in her figures, the presence of a 

 'finger-formigen Plasmafortsatz,' the fate of which is left in 

 doubt. The later stages in metamorphosis are taken from the 

 history of the spermatozoon of Ixodes. The mature sperma- 

 tozoon is figured and described, and the statement is made that 

 in the processes of its formation the head of the inner tube 

 pushes its way through the outer, but the manner in which this 

 evagination leads to the formation of a single tube is not defi- 

 nitely indicated. An apical organ is described and its origin 

 from material within the completed tube is suggested together 

 with the relation of this body to the nucleus. The presence of 

 a flagellum-like structure ('geissel') within the nuclear end of 

 the tube is indicated, but no stage is figured in which this 

 flagellum projects from the tube as it does in Argas, although 

 supposedly mature spermatozoa of both Ixodes and Ornithodoros 

 are shown. Samson reviews the work of Christophers, Bonnet 

 and Nordenskiold, pointing out some of their errors, to which 

 further reference will not be made in this paper. 



SUMMARY AND CONCLUSION 



In the spermatocytes of Argas miniatus toward the end of 

 the growth period three distinct types of cytoplasmic inclusions 

 may be recognized. These are designated true mitochondria, 

 extra-nuclear bodies and vesicular bodies. The outer surface 

 of the cytoplasm is differentiated to form a honeycomb-like 



