Gemara

(Mishnah - R. Yehudah): If one was Makdish an empty pit, wasteheap or dovecote, and it became full of water, manure or doves, Me'ilah applies to it, but not to what came later.

R. Yosi says, if one was Makdish a field or a tree, Me'ilah applies to it and to what grows, for what grows is Hekdesh.

Rebbi taught that R. Yosi agrees with R. Yehudah about a pit and dovecote. R. Yosi argues only about a field and tree.

(Beraisa): If one was Makdish them when they were empty and then they became full, Me'ilah applies to them, but not to what came later;

R. Elazar b'Rebbi Shimon says, Me'ilah applies also to what came later.

(Rabah): They argue about a pit and dovecote. All agree about a field and tree, that Me'ilah applies to them and their contents.

The first Tana holds like Chachamim, that one cannot be Makneh (transfer ownership, or be Makdish) Davar she'Lo Ba l'Olam (something that is not yet in the world). R. Elazar b'Rebbi Shimon holds like R. Meir, that one can transfer ownership of it.

Question: R. Meir said so only regarding fruits of a date tree, for they normally grow. An empty pit or dovecote will not fill itself!

Answer (Rava): The case is, the pit is at the bottom of an incline (water normally flows into it), and the dovecote is near a thriving dovecote (presumably, offspring from the full dovecote will inhabit the empty one).

Zevachim 45a (Beraisa): One may not benefit from Kodshim of Nochrim. One who benefited did not transgress Me'ilah.

One may not benefit from them mid'Rabanan. We learn that Me'ilah does not apply to them from a Gezerah Shavah "Chet-Chet" from Terumah. Regarding Terumah it says "Bnei Yisrael."

Rishonim

Rambam (Hilchos Me'ilah 5:6): Me'ilah applies to things that grow from Hekdesh. If one was Makdish a field and it grew herbage, or a tree and it produced Peros, Me'ilah applies to them. However, if one was Makdish an empty pit, wasteheap or dovecote, and it became full of water, manure or doves, since they do not grow from Hekdesh, Me'ilah does not apply to them.

Rashbam (79a DH Hachi): Hekdesh is not strong enough to acquire through its Reshus. Regarding a person, we learn that his Chatzer acquires for him from "v'Im Himatzei Timatzei v'Yado."

Tosfos (79b DH Eimar): Even if the water and doves are likely to come, how does Hekdesh acquire? Hekdesh has no Chatzer! One cannot be Makdish what is not in his Reshus and will never come to his Reshus! The Rashba answers that he was Makdish the pit or dovecote on condition that he retains rights in them to be able to acquire the water and doves for Hekdesh.

Ramban (79a DH v'Ha): The Rashbam explains that Me'ilah does not apply to what is in them because Hekdesh has no Chatzer, for Chatzer works due to Yad and Hekdesh has no Yad. One could say that a Chatzer acquires for Hekdesh, but Me'ilah does not apply to what it acquires.

Ketzos ha'Choshen (DH v'Nistapakti): Perhaps only a Chatzer of Hekdesh does not acquire for Hekdesh, but if a person said 'my Chatzer should acquire for Hekdesh', it acquires. Or, perhaps even this does not work. It seems that it works. Rava (Nedarim 34b) taught that if one said 'my Chatzer should acquire this (Hefker) loaf for Hekdesh', Me'ilah applies to it. The Ran says that one's four Amos acquire for Hekdesh, like Ploni can acquire a Metzi'ah for Reuven. Four Amos acquire like a Chatzer. This is a proof for Tosfos and the Rashbam, that Hekdesh has no Chatzer. If Hekdesh has a Chatzer, but Me'ilah does not apply to what it acquires, why does Me'ilah apply to this loaf? What is the difference whether Hekdesh acquired through Zechiyah of its own Chatzer, or through a person's Chatzer? In both cases a person was Makdish it through Zechiyah! This proves that Me'ilah applies to Hekdesh through Zechiyah. We must say, like Tosfos (Zevachim 45a DH Dumya), that Kodshei ha'Guf of Nochrim are excluded from Me'ilah, but not Kodshei Bedek ha'Bayis. Me'ilah applies to the loaf, for it is Hekdesh Bedek ha'Bayis. I proved that a person's Chatzer can acquire for Hekdesh. If so, why did Tosfos (79b DH Eimar) need to say that he keeps rights in the pit to be able to himself acquire the water for Hekdesh?! It is because a Chatzer acquires due to Shlichus, and one cannot make a Shali'ach for Davar she'Lo Ba l'Olam (Nazir 12b), his words help only according to R. Meir, who holds that one can be Makneh (or make a Shali'ach for) Davar she'Lo Ba l'Olam.

Poskim

Question (Tosfos Yom Tov Me'ilah 3:6 v'Ein): Why does Tosfos say that Hekdesh has no Chatzer, for it has no Yad? We conclude (Bava Metzia 12a) that even though Chatzer acquires like a Yad, it is no worse than Shlichus. Hekdesh has Shlichus! Kohanim who serve in the Mikdash are Hash-m's Shluchim (Nedarim 35b)! When the Gizbar is near the Chatzer, it is guarded, and it should acquire for Hekdesh! It is difficult to say that the Gizbar is a Shali'ach, and a Shali'ach cannot make a Shali'ach.

Answer #1 (Tzon Kodoshim Me'ilah 13a DH Tosfos): The Tosfos Yom Tov overlooked Tosfos Kidushin 23b (DH d'Omar), which concludes that the question was whether Kohanim are only Hash-m's Shluchim, or Shluchim of Hash-m and of Yisrael. Since the question was not decided, we can say that they are also Yisrael's Shluchim, so the Gizbar cannot acquire for Hekdesh without Da'as of the owner.

Rebuttal (Ketzos ha'Choshen 200:1): Even if Kohanim are Shluchim also of Yisrael, surely the Gizbar is Hash-m's Shali'ach. The question was about Kohanim, for they offer Yisrael's Korbanos. The Tosfos Yom Tov merely proved from here that Shamayim can have Shluchim. Also, Tzon Kodoshim said that the Gizbar cannot acquire for Hekdesh without Da'as of the owners. A Hefker object has no owner! Water and manure come from elsewhere and have no owners. They are Hefker.

Answer #2 (Ketzos ha'Choshen): In Gitin (21a), Abaye says that Chatzer acquires like a Yad, but Shlichus is not due to Yad. Tosfos (21a DH Atu) asks that we conclude (Bava Metzia 12a) that Chatzer acquires like a Yad, but it is no worse than Shlichus. It is Zechus to acquire a Metzi'ah, so one acquires even if he is not standing nearby. It is unlike a Yad. It acquires due to Shlichus; Zachin l'Adam she'Lo Befanav (one may acquire for someone in his absence). However, in other respects it must be like a Yad. This is why a moving Chatzer does not acquire like a Shali'ach. The Shitah Mekubetzes (12a) says that the Hekesh of Chatzer to Yad teaches that it must resemble a Yad. Since Hekdesh has no Yad, it has no Chatzer, for a Chatzer acquires like a Shali'ach only when it is like a Yad.

Answer #3 (Nesivos ha'Mishpat 200 Hakdamah DH ul'Fi): The Ran (Bava Metzia 12a) says that a Chatzer cannot acquire a Metzi'ah due to Shlichus, for we require Shlichus of the owner. Also, this harms others (who might want to acquire it). Therefore, it can acquire only due to Yad. Even though the Ran says that a Chatzer can acquire a Metzi'ah due to Shlichus mid'Rabanan, perhaps this is only for a person, just like it was enacted that a person acquires through his four Amos, and this does not apply to Hekdesh. However, we do find that Hekdesh has a Yad, i.e. the Gizbar (Shach 255:6)! It seems that this does not help for a Metzi'ah, for the Gizbar is Hash-m's Shali'ach, and we require Shlichus of the owner. Also, this harms others. Just like Hash-m did not make the Gizbar a Shali'ach to acquire for one person and harm another, he is not a Shali'ach to acquire for Hekdesh and harm others. The Ramban agrees to this. The Ran (Nedarim 34b DH Omar Rava) says that one can acquire a Hefker loaf for Hekdesh through his Chatzer. There is different, for he has a Migo, i.e. he could acquire it for himself. This does not apply to a Chatzer of Hekdesh. The Ramban discusses a pit or dovecote that became full of water or doves, in which there is no loss to anyone else. If not for the pit or dovecote, there would be no water or doves. Hekdesh caused them to come. In such a case, the Gizbar is a Yad of Hekdesh and Hash-m's Shali'ach. Also, we do not require Shlichus of the owner regarding Hefker. We require it for a Metzi'ah, for as long as no one else acquired it, it still belongs to the one who lost it. This is why Har ha'Bayis does not acquire money dropped there. Surely, if one gives to Hekdesh, even if he did not give to the Gizbar, rather, he put it in a Chatzer of Hekdesh, in front of the Gizbar, Hekdesh acquires. Here there is Shlichus of the owner, and it does not harm others.