GERM CELLS OF ARGAS 645 



roost where they are often found in enormous numbers. During 

 the day the adults and nymphs conceal themselves in cracks 

 and crevices between the boards of the hen-house and from 

 these hiding places they issue at night to prey upon the fowls. 

 Only the seed ticks or newly hatched nymphs feed continuously 

 upon the fowls, and this period lasts from but three to ten days. 

 The life-history, habits and distribution of Argas are well de- 

 scribed by Bishopp ('13). 



All but the final stages in the development of the male germ 

 cells of Argas may be obtained from the testes and sexual ducts 

 of the male. The testes are two long tubes which lie loosely 

 coiled within the body. Longitudinal sections through the testes 

 reveal the germ cells in successive stages of development from 

 the early spermatogonia onward, and such sections make possi- 

 ble the study of many stages from the same slide where they 

 have all been subjected to the same fixing and staining technique. 

 The final stages in development occur within the spermatophore 

 sacs in the genital ducts of female and as the spermatozoa 

 leave the spermatophores. 



Both sections and smear preparations were employed and 

 numerous observations were made upon the living cells both 

 with and without vital dyes. Many fixing solutions were used, 

 the most satisfactory being Flemming's stronger solution, and 

 the fluids of Altmann, Benda, Meves and Bensley. Osmic acid 

 (in 2 per cent solution and in the form of vapor) also gave good 

 results. Bichromate-formalin was less satisfactory. The mix- 

 tures of Carnoy, Gilson and Bouin were used for purposes of 

 comparison. Bensley's acid fuchsin with counter stain of methyl 

 green, methyl blue, or toluidin blue gave the best differential 

 results for mitochondria although the alizarin-crystal-violet 

 method of Benda (or Duesberg's modification) is equally satis- 

 factory in certain stages of development. Haidenhain's iron- 

 haematoxylin was employed after all fixatives for comparison. 

 As vital stains for mitochondria janus green (Hoechst) and its 

 derivative diethylsafranin are most satisfactory. Certain spe- 

 cial dyes, brilliant cresyl blue B extra, Sudan III, and others 

 were found valuable for analysis. Prolonged study of the living 



