Spermatogenesis in Asilus notahis Wied., (Diptera). 
449 
Plate XXIII. 
Figs. 26 — 30. Asilus notalus, late growth period and spermatocyte divisions. 
Fig. 26. Sliglitly later than the contraction stage sliown in fig. 25; the diplotene 
threads arebecoming well separated; six threads and tbe nucleolus are present; nucleus 
entire. 
Fig. 27. Somewhat later, the diplotene threads are becoming more Condensed; 
nucleus entire. 
Fig. 28. Early prophase of the first division; the nucleus is entire, showing the six 
long bivalents and the Condensed XY pair derived from the nucleolus. 
Fig. 29. Later prophase showing the condensation into the seven chromosomes of 
the first division. 
Fig. 30. First spermatocyte metaphase in polar view. 
Fig. 31. Second spermatocyte metaphase in polar view. 
Fig. 32. Two poles of an anaphase of the second division showing the complement 
of seven chromosomes that goes into each spermatid; some chromosomes shown in end 
view. 
Literature cited. 
Davis, H. S. 1908. Spermatogenesis in Acrididae and Locustidae. Bull. Mus. Comp. 
Zool. Harvard. Vol. 52. Xo. 2. 
.Metz, C. W. 1916. Cliromosome studies on the Diptera. II. The paired association 
ofcluomosomes in the Diptera and itssignificance. Journ. Exp. Zool. Vol. XXI 
No. 2. August 1916. 
Metz, C. W. 1922. Clu-omosome studies on the Diptera. IV. Incomplete synapsis 
of chromo omes in Dasyllis grossa Fahr. Biol. Bull. v. 43, no. 4, Oct. 
Metz, C. W. and Jose F. Nonidez. 1921. Spermatogenesis in the Fly, Asilus sericeus Say. 
Journ. Exp. Zool. Vol. XXXII. No. 1. 
Wilson, E. B. 1912. Studies on chromosomes VIII. Journ. Exp. Zool. Vol. XIII. 
pp. 345 — 149. 
