The middle part of the mishna reads (Danby trans.):
A man may give a maah to a wine-seller or a baker to secure for him a share in an eruv. So R’ Eliezer. But the Sages say: His money [alone] cannot secure for him a share. But they agree that with any others his money can secure for him a share [i.e., if he had so spoken to any person other than bakers].
The Yerushalmi has a stunning discussion on this point:
R’ Abahu in the name of R’ Yochanan: “This tells us that money does not acquire on a Torah level.” If so, even if he came to him, to the storekeeper? That is different, as he might forget and expend it [or, send it out – “yotzi’enu”]. R’ Acha in the name of R’ Chanina: “Father did not say it thus. Rather: ‘But the Sages say: His money [alone] cannot acquire for him’ – this tells us that money does acquire on a Torah level.”
The Meforshim have grave difficulty with this passage, and emend it. The Mashbiach makes it simple:
R’ Abahu’s statement in the name of R’ Yochanan focuses on R’ Eliezer’s statement in the mishnah. R’ Eliezer’s stress “in an eruv” indicates that this halacha that a maah secures wine or bread is unique to eruvin – a leniency because eruv is Rabbinic. On that the Yerusalmi asks, well, if it’s only d’Rabbanan, then “even if he [just] came” – to the storekeeper, without any money whatsoever, and asked him to designate a loaf for him, why does that not suffice? The Gemara responds that in that case we are afraid the storekeeper will forget the designation and sell [“send”] the bread to someone else.
R’ Acha says in the name of R’ Chanina (R’ Abahu’s son – Lieberman) that what his father actually said was that from the words of the Sages we see that although money does acquire me’dorysa, and it is only d’Rabbanan that money does not acquire, the Sages sustained their takkanah that money does not acquire even vis a vis a d’Rabbanan, i.e., eruv.
BTW, later on the amud, there is an amazing Gilayon ha’Shas (which, in the Yerushalmi, is not R’ Akiva Eiger but R’ Yosef Shaul Nathanson) in which he proposes to explain the Gemara’s statement that our mishna is the opinion of R’ Meir that requires both shittuf and eruv to mean that eruv itself requires *both* bread *and* wine, not bread alone.
Kol Tuv,
YGB