Recapitulation is a bold and influential idea that is particularly associated with Ernst Haeckel though many other biologists also supported it in the nineteenth and early twentieth centuries. According to the theory of recapitulation, the stages of an organism’s development correspond to the species’ phylogenetic history- in a phrase, “ontogeny recapitulates phylogeny.” Each stage in development corresponds to (that is, [...]
Here is a list of seven effective physical agents that can kill infection causing organisms:- 1. Electricity 2. Sonic and Supersonic Waves 3. Alpha, Beta, and Gamma Rays 4. Electrons 5. Cathode Rays 6. X Rays 7. Distilled Water. Physical Agent # 1. Electricity: Beattie and Lewis (1920) employed a current of about 4000 volts and 2 amp. for 4 [...]
Among the various methods followed for controlling microbial activity, the best by far is sterilization as it eliminates all the microbes. Sterilization is achieved by the following methods: 1. Physical Methods 2. Radiation Methods 3. Ultrasonic Methods 4. Chemical Methods. 1. Physical Methods: Physical methods of sterilization include killing of microbes by applying moist heat as in steaming or dry [...]