Figure 4

Frequency distributions of the number of first spermatocytes ( F ) and spermatids ( S ) per cyst in D. hydei and D. melanogaster (redrawn from [19]). Note a) that not all cysts contain the expected F = $2^{n_{\text{t}}}$ spermatocytes, but that F can deviate both above and below the expected values by small increments, b) that the number of spermatids per cyst (S) approximately reflects the patterns in F, but that the mode of the two distributions can be somewhat shifted relative to each other, and c) that in D. melanogaster both the F and S distributions are clearly bimodal.