166 Dr. M. Verworn's Biological Studies of Protista. 



the zone of chamberlets to which this sarcodic ring gave 

 origin is formed upon the perfected tyye^ without any reversion 

 to the earlier Peneropline stage." The last remark refers to 

 Carpenter's observation that the shell of Orhitolites from its 

 earliest foundation passes through various developmental 

 stages, in which it resembles other Polythalamian shells — 

 Cornuspira, Spiroloculina, Peneroplis^ and Orhiculina. In 

 the same degree as in Orhitolites tenuissima^ Carpenter also 

 met with the phenomena of regeneration in Orhitolites com- 

 planata, Lam., a form which is remarkable for the enormous 

 number of its small-chambers and its narrow annuli. Quite 

 a small fragment suffices to induce the new-formation of a 

 large individual. As regards the relations of the nucleus in 

 the Orhitolites^ Carpenter found in the protoplasmic mass of 

 the Polythalamian a great number of small round corpuscles, 

 which were irregularly scattered. He assumes these to be the 

 nuclei of the Protistan. Moreover, that this Polythalamian 

 form is multinuclear is rendered extremely probable by the 

 intense phenomena of regeneration of the most various 

 fragments. 



In conclusion, a brief summary of the results obtained and 

 a critical discussion of them may not be out of place. The 

 result of the observations and experiments on Diffl,ugia urceo- 

 lata is as follows : — The construction of the carapace is 

 effected in the same way as in the other shelled freshwater 

 Ehizopoda, with this difference, that foreign bodies for the 

 structure of the shell are incepted into the protoplasm by 

 certain reflex processes. Regeneration of the injured or com- 

 pletely removed shell by the protoplasmic body does not 

 occur, although the vital functions take their course in the 

 normal fashion. The experiments on Polystomella crista 

 show quite a different result. It appears that phenomena of 

 regeneration are manifested in a fragment if the nucleus is 

 contained in it, but that they never appear when the nucleus 

 is absent. The observed processes of regeneration consist on 

 the one hand in the healing of the wound by a deposition of 

 calcareous matter, which is secreted by the surface of the 

 protoplasm, and on the other in the formation of new chambers. 

 On the contrary, the reparation of separate injured portions, 

 such as, for example, the remains of the tubular system, never 

 took place. \\\ Orhitolites tenuissima axuicomjjlanata, finally, 

 the process of regeneration occurs in the same manner, with 

 the sole exception that the formation of new chambers upon 



