ON THE ORIGIN OF DEATH. 1 23 



unless their life-history is much less well known than 

 bacteriologists and botanists think, these forms are 

 potentially immortal. The Infusoria are the highest 

 and most differentiated of unicellular forms. They 

 have organs of locomotion, mouth, pharynx, some sort 

 of excretory apparatus, myophanes (muscle-like struc- 

 tures), trichocysts, etc. ; while in the lowest organisms 

 none of these organs are to be found. Further, the 

 Infusoria have a macro-nucleus which Maupas shows is 

 vegetative in its function, and a micro-nucleus which 

 is generative. If the macro-nucleus is lost, nutrition 

 fails, and if the micro-nucleus is lost, conjugation is im- 

 possible. In the lower Protozoa no such differentiation 

 has been observed. There is merely one nucleus, which 

 is surrounded by a mass of protoplasm. 



In a recent article Biitschli maintains that in the 

 Bacteria the whole body is the nucleus, and that the 

 surrounding mass of protoplasm, such as characterizes 

 the Rhizopods, is absent. Between the Bacteria and 

 Infusoria there is a wide gap in the zoological scale. 

 Now is it not possible that as the Infusoria were evolved 

 from lower and simpler forms, the process of conjugation 

 was first acquired ? That when, in the cycle of meta- 

 bolic changes the protoplasm fell short of the point 

 from which it started and to which it should return, 

 this deficiency was made up by foreign substance ob- 

 tained from an individual of different origin, and there- 

 fore of different material ? Those of the primitive 

 forms which retained their original immortality have 

 left lineal descendants which we know to-day as Bac- 

 teria. Those which in a measure lost that power have 

 either become extinct or else acquired a habit of re- 



