ABSTRACT
This chapter discusses the case of two spatial dimension to study the diffusion with an increasing quantity of substance. In addition to diffusion, there is also a growth of the quantity of the substance, and at each point and each moment this growth is occurring at a rate depending on the density then observed. The chapter derives the diffusion equation for the study with the help of theorems and their proofs. It also applies the theorems to the study of some biological problems.
