To dr. farr:
Thanks but you know I rely on sources that are available for everyone. I have neither JSTOR access nor unique manuscripts at hand, only a fairly good academic library and that is all. Information is in front of us, we must only pick it up.
To Martin:
Instead of hunting the outdated edition of Riess (which I do not have in copy), I would suggest you using the modern editions of Boer and Weinstock for Porphyry 38 in CCAG 5.4 (downloadable from Chris Brennan's webpage) and of Pingree for Hephaestio II 1, 2 and III 10, 5.
Regarding Yavanaj?taka, while all chapter 5 is about conception, which has a more direct link to Hellenistic theories is verse 19, as it seems to have a remark on the time of birth compared to conception. (Perhaps it is the source for Var?hamihira,
B?hajj?taka 4, 21.) That is all why I picked it up. Anyway, I collected sources not only for the Trutine of Hermes but for issues on conception altogether, as they seem to be interrelated.