300 GENERAL PHYSIOLOGY 



tated in the form of liquid. Further, he justly lays the greatest 

 value upon the principle that the organisms that arose by 

 spontaneous generation must have been, not cells but the lowest 

 and simplest organisms that can be imagined, " completely homo- 

 geneous, structureless, formless lumps of proteid." It is con- 

 ceivable that these living proteid lumps arose from the mutual 

 action of substances dissolved in the primitive sea. But Haeckel 

 expressly refuses to discuss in detail the " how " of their origin : 

 " Every detailed portrayal of autogony is for the present inadmis- 

 sible, for the reason that we can form absolutely no satisfactory 

 idea of the peculiar condition presented by the earth's surface at 

 the time of the first appearance of organisms." From the very 

 simple and low organisms that arose spontaneously, which on 

 account of their simplicity Haeckel termed Monera, there have 

 been derived by continuous descent the cells and all forms of 

 organisms that to-day inhabit the earth's surface. 



This in its essentials is the doctrine of spontaneous generation 

 in its present form. Notwithstanding the fact that its conclusion is 

 so simple and obvious, it has been contradicted on many sides and 

 has led to the establishment of other theories upon the origin of 

 life upon the earth. 



2. The Theory of Cosmozoa 



The theory of germs of lower organisms capable of life moving 

 about in space, or, as Preyer has termed it in brief, the theory of 

 cosmozoa, was the first to appear in recent times in opposition 

 to the doctrine of spontaneous generation. Its founder was 

 H. E. Richter ('65, 70, and 71). Starting from the idea 

 that small solid particles are moving about everywhere in space 

 and in the rapid flight of the heavenly bodies are continually 

 being stripped off from them, Richter assumes that, at the same 

 time and attached to these solid particles, germs of micro- 

 organisms capable of life are also continually being thrown off 

 from such heavenly bodies as are inhabited and carried to others. 

 If such germs come to other heavenly bodies whose state of develop- 

 ment presents favourable vital conditions, especially moderate heat 

 and moisture, they begin there to develop and become the starting- 

 point of a host of organisms. Somewhere in space, Richter thinks, 

 there have always been heavenly bodies upon which life exists in 

 the form of cells. The existence of living cells in the universe is 

 eternal. " Omne vivum ab ceternitate e cellula" says Richter, modi- 

 fying anew, according to the precedent of Virchow, Harvey's old 

 dictum. Organic life, therefore, has never originated but has 

 always been transferred from one world to another. Thus, 

 according to Richter, the problem of the origin of life upon the 

 earth is not : How has life arisen upon the earth ? but : How has 



