BUDDING 293 



taneous generation where it was believed non-living ma- 

 terial becomes transformed into living substance. Fishes 

 and frogs were thought to be developed from mud, many 

 insects from the juices of plants, and a horde of organisms 

 was supposed to originate in decomposing masses of 

 organic matter. In the Middle Ages certain physicians 

 maintained that scorpions were generated in a plant, the 

 sweet basil, and the public was warned against smelling 

 it lest scorpions be generated in the brain and insanity 

 result. Even in our own day we hear of horsehairs that 

 are said to change into snakes, and earthworms and 

 mosquitoes that rain from the sky. 



Doubt was first cast on such a belief by the Italian 

 naturalist Redi, who in 1660 performed the simple experi- 

 ment of tying gauze over the mouth of a jar containing 

 decaying meat, and proving that fly maggots were not 

 spontaneously generated. Other investigators experi- 

 mented with different forms of life with the same result. 

 The bitterest fight was waged about the bacteria, or 

 minute plants, which in some cases at least did appear 

 to arise spontaneously. In 1861, Pasteur, the great 

 French scientist, took the field, and as a result of care- 

 fully safeguarded experiments showed that even here 

 spontaneous generation does not occur. Incidentally it 

 may be added that Pasteur's work laid the foundation for 

 the science of bacteriology. 



Budding. — In asexual reproduction there are two main 

 types — unequal division of the body or budding (Fig 69), 

 and equal division known as fission (Fig. 4) . At first sight 

 it may appear that this is a somewhat artificial distinc- 

 tion, but in reality it is of fundamental importance, as 

 will appear later. 



Hydra (Fig. 7) affords an excellent example of bud- 

 ding in which the first indication is a pouch-like out- 

 growth of the body-wall of the side of the animal. As 

 this increases in size tentacles and mouth appear on the 

 free extremity, and after further growth the bud con- 



