Bava Batra 66: Attached to the Land is Part of the Land

A hollowed out tube that sits on land is considered to be part of that land.  What about a beehive?  The rabbis discuss whether or not a beehive is like a tree which is also attached to the ground.  Would collecting honey from a beehive on Shabbat be subject to a sin-offering?  They also consider whether or not the beehive would be a source of ritual impurity.  Other cases are compared, including that of a hollowed out tube filled with collected water; that water would not be ritually pure enough to contribute to a mikvah because the tube would act as vessel, and its water would be classified as "drawn water".  

The rabbis compare this to the baker's board attached to a wall.   It was considered to be unattached to the wall, and not like 'land' - thus a baker's board was a vessel with no receptacle and susceptible to ritual impurity.  However, Rabbi Eliezer seems to believe that anything that is attached to land or attached to something else that is attached to land is not susceptible to ritual impurity. The rabbis wonder whether it might make a difference if the board were made of metal.

The rabbis note that some stringencies, like the drawn water invalidating a mikvah, were rabbinical in origin.  

The Gemara looks more deeply at the concept of movable versus permanent attachments to the ground.  Again, Rabbi Eliezer holds that anything attached to the ground holds the status of 'land'.  What about millstones, which begin as movable stones but are then placed permanently?  When rain falls on the millstones, are the seeds still valid to use or have we broken the transgression regarding water (or other liquids) coming into contact with seeds before they are processed?  Does it matter whether or not the owner was hopeful that there would be rain?  

Finally the rabbis tell a story about using one tenth of a father's property - in the form of millstones - as his daughter's dowry.  In fact, another tale teaches that even rent money could be used for one's dowry, for it is considered to be close enough to 'property' to be considered money that has come from one's land.