A (2)

无性蠕虫或完全裂殖的品系（OH株）的雌雄同体的生殖器官，并最终进行有性生殖，而不是无性生殖，即分裂，如果它们被一种完全卵生的涡虫，Bdellocephala brunnea，这表明性成熟的蠕虫具有性化物质。完全性化的蠕虫不再需要以性蠕虫为食来维持性。在这里，我们证明了性化的蠕虫产生足够的它们自己的性化物质，类似于B中所含的物质。brunnea。在手术切除有性化蠕虫的情况下，具有性器官的片段再生为有性，而没有性器官的片段，即头部片段，再生为恢复无性状态。来自有性化蠕虫的无性再生体也通过用B喂养而完全有性化。brunnea。此外，据报道，性成熟蠕虫的头部区域缺乏完全性化所必需的假定性化物质（Sakurai，1981）。这些结果表明，没有性器官的片段缺乏足够量的假定的性化物质，并且性化的蠕虫中含有的性化物质维持性。

Asexual worms or an exclusively fissiparous strain (the OH strain) of the planarian Dugesia ryukyuensis keep developing hermaphroditic reproductive organs and eventually undergo sexual reproduction instead of asexual reproduction, namely fission, if they are fed with sexually mature worms of an exclusively oviparous planarian, Bdellocephala brunnea, suggesting that the sexually mature worms has a sexualizing substance(s) The fully sexualized worms no longer need the feeding on sexual worms to maintain the sexuality. Here, we demonstrate that the sexualized worms produce enough of their own sexualizing substance similar to that contained in B. brunnea. In case of surgical ablation of the sexualized worms, the fragments with sexual organs regenerate to become sexual, while those without sexual organs, namely head fragments, regenerate to return to the asexual state. The asexual regenerants from the sexualized worms are also fully sexualized by being fed with B. brunnea. Additionally, it was reported that head region in sexually mature worms lacks the putative sexualizing substance necessary fir complete sexualization (Sakurai, 1981). These results suggest that the fragments without sexual organ lack enough of an amount of the putative sexualizing substance and the sexuality is maintained by the sexualizing substance contained in the sexualized worms.