R. Tarfon holds that Keren in Reshus ha'Nizak pays Nezek Shalem, while the Chachamim hold that it pays Chatzi Nezek.
R. Tarfon holds that the Din of Dayo does not apply if the Kal va'Chomer would no lo longer be made.
Shichvas Zera is Mitamei with Maga (touching).
R. Elazar says that the Shichvas Zera of a Zav is Mitamei with Maga but not with Masa.
R. Yehoshua says that the Shichvas Zera of a Zav is also Mitamei with Masa because it is impossible that there isn't a little bit of Zivah mixed in.
The Zovo of a Zav, his spit, Shichvas Zera, urine and the blood of a Nidah is Mitamei with Maga and with Masa. (1)
Small earthenware jugs do not susceptible to Tum'as Zav but they are susceptible to Tum'as Mes and Sheretz. (2)
A reed mat is susceptible to all types Tum'ah. (3)
A Sheretz the size of a lentil is Mitamei while a Mes is only Mitamei if it is the size of an olive.
It is a Machlokes if a Din that is being learned out takes all of the Dinim of what it is learning it out from.
All Tum'os from a Mes are not Tamei for less than seven days.
Shen and Regel are Patur in Reshus ha'Rabim.
A BIT MORE
1. This Keri of a Zav is learned out with a Kal va'Chomer from spit that it is Mitamei with Maga and Masa.
2. Earthenware utensils only become Tamei from the inside and small jugs that are too small for the Zav to put his finger inside cannot become Tamei with Maga and since they do not become Tamei Maga they also do not become Tamei Heset.
3. Even though it is not a utensil it is suitable for Mishkav and it is susceptible to Tum'as Midras of a Zav and all other Tum'as are learned out from Zav.