and a little ether are allowed to flow, the pseudopod formation of the amœbæ ceases within a few minutes and they all assume the shape of a ball. (Figure 62.) In asphyxiation in pure nitrogen, the changes in the amœbæ take place in exactly the same manner with the exception that in this case a longer period ensues according to the size and activity of the animals. About 20 to 60 minutes elapse before depression becomes complete. If larger sea rhizopoda are narcotized in the same manner all pseudopods are more or less retracted and the contained protoplasm flows centripetally and contracts in the characteristic manner into balls and spindles. (Figure 63.) If the narcosis is removed by displacing the ether by pure air, the stretching out of the pseudopods then begins anew, provided the narcosis has not been too deep or too prolonged. [221] _Max Verworn_: “Die physiologische Bedeutung des Zellkerns.” Pflügers Arch. Bd. 51, 1891. The same: “Die Bewegung der lebendigen Substanz. Eine vergleichend-physiologische Untersuchung der Contractionserscheinungen.” Jena 1892. The same: “Allgemeine Physiologie.” V Auflage. Jena 1909. In the last place the same theory of the contraction movements with some new corrections is described. [Illustration: _A_ _B_ Fig. 62. Amoeba limax. _A_--In normal state. _B_--Narcotized by ether.] [Illustration: Fig. 63. Rhizoplasma Kaiseri. Effect of chloroform.] In the face of all this evidence there can be indeed no further barrier to the assumption that the symptoms in narcosis are a result of a suppression of the oxydative processes. Nevertheless, I would not at present venture to maintain that the entrance of the narcotic into living substance produces no alterations whatever, except just this oxydative suppression. For the present it seems to me that the possibility is in no way precluded that the same process, which is expressed in the oxydative suppression, is connected with other alterations in the living substance, of which we are as yet ignorant. As far as the effects of larger doses of narcotics are concerned, the assumption that other alterations take place in the living substance can in any case hardly be avoided. An application of larger quantities of narcotics brings about destruction of the living system with great rapidity. Here the alterations in the optical properties of the cell are of such magnitude that the changes are directly perceptible under the microscope. _Binz_[222] has observed such alterations in the nerve cell and looked upon them as coagulation. In unicellular organisms these optical alterations can readily be followed. If amœbæ, sea rhizopods or infusoria are narcotized with stronger doses of ether or chloroform, the protoplasm becomes opaque and granulated, it appears darker than formerly and in many cases displays a yellowish brown color in transmitted light. Cells altered in this way no longer recover after removal of the narcotic. These intense and rapidly appearing