This paper presents a mathematical model of normal and abnormal tissue growth. The modelling focuses on the potential role that stress responsiveness may play in causing proliferative disorders which are at the basis of the development of avascular tumours. In particular, we study how an incorrect sensing of its compression state by a cell population can represent a clonal advantage and can generate hyperplasia and tumour growth with well known characteristics such as compression of the tissue, structural changes in the extracellular matrix, change in the percentage of cell type (normal or abnormal), extracellular matrix and extracellular liquid. A spatially independent description of the phenomenon is given initially by a system of nonlinear ordinary differential equations which is explicitly solved in some cases of biological interest showing a first phase in which some abnormal cells simply replace the normal ones, a second phase in which the hyper-proliferation of the abnormal cells causes a progressive compression within the tissue itself, and a third phase in which the tissue reaches a compressed state, which presses on the surrounding environment. A travelling wave analysis is also performed which gives an estimate of the velocity of the growing mass.

The determination of faecal elastase 1 concentration is a simple and reliable means of assessing exocrine pancreatic function in children with cystic fibrosis. Results are not influenced by non-pancreatic disorders or by enzyme supplementation.

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Political clientelism in Southern Italy has shown great persistence and capacity for conditioning the entire Italian political development. Accounting for these characteristics, clientelism is better understood as the product of the incomplete capitalistic rationalization of the Southern economy. Throughout the 19th century in Sicily, the feudo remained the basis of the economic and social structure, while in the continental South the feudal system disintegrated more quickly and widely. The resulting different models of social relationships within the Mezzogiorno, make it meaningful for our purposes to distinguish between two types of clientele, which may be termed clientela mafiosa and Neopolitan clientele. The second part of the article is concerned with the dynamics of the clientelistic system in post‐1945 Southern Italy and more generally with the relationship between clientelism and political development. The transition from the clientelism of the notables to political party‐directed patronage is studied both at the local level and in the context of the whole South. It is then argued that clientelism is a very poor tool for political development since it has two effects on the social structure and the political process: these effects will be called disorganic integration and exclusivism.

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