1. P. S. Chen andF. Baltzer, Exper.18, 522 (1962).
2. P. S. Chen andF. Baltzer, Exper.20, 236 (1964).
3. A. H. Whiteley andF. Baltzer, Pubbl. Staz. Zool. Napoli30, 402 (1958).
4. F. Baltzer, Arch. Zellf.5, 497 (1910).
5. F. Baltzer andP. S. Chen, Rev. suisse Zool.67, 186 (1960).