Balbiani (’88) found that non-nucleated pieces of cytrostomum, trachelus, and protodon failed to regenerate, and Verworn (’89 and ’92) obtained similar results on several other protozoa. Similar facts have been made out by Hofer (’89), Haberlandt and Gerassimoff (’90). Palla (’90) found that in certain cases non-nucleated pieces, especially those from cells in growing regions, can produce a new cell wall; while more recently Townsend (’97) has shown in several forms that non-nucleated pieces do not produce a new cell wall unless they are connected by protoplasmic threads with nucleated pieces. The most delicate connection suffices to enable a non-nucleated piece to make a cell wall, even when the nucleated piece lies in one cell and the non-nucleated in another, the two being connected by a thread of protoplasm that passes through the intervening wall. If we examine somewhat more in detail some of these cases, we find that when a form like stylonychia is cut into three pieces, the two end-pieces without a nucleus fail to regenerate, while the central piece makes a new entire organism of smaller size. If stentor is cut into three pieces, each piece containing one or more nodes of the macronucleus, each produces a new stentor. If, however, a piece is cut off so that it does not contain a part of the macronucleus, it fails to regenerate. Verworn (’95) succeeded in removing the central capsule with its contained nucleus from the large radiolarian, _Thallasicolla nucleata._ The non-nucleated animal remained alive for some time, but eventually died. The nucleated capsule developed a new outer zone with processes like those in the normal animal. If the nucleus is taken from the capsule, the capsule dies, but shows some traces of the formation of an outer zone. If the protoplasm is removed as far as possible from around the nucleus, the latter does not regenerate new protoplasm, but dies after a time. Verworn concludes that the protoplasm cannot carry on all its normal functions without the nucleus, or the nucleus without the protoplasm.