Hemolysis considered as a progressive reaction in a heterogeneous system

It is demonstrated, without the use of special assumptions, that red cells are heterogeneous with respect to their resistance to at least certain lysins, that the reaction between the cell components and the lysin is virtually irreversible in some cases but reversible, although to different extents, in others, and that the lysin initiates a process in the cell which is not adequately described by the terms reversible and irreversible, but rather by the term progressive. Progressive reactions, i.e. reactions which cannot be stopped once they are well under way, may be looked for in systems which have structure, and in which local reactions occurring at strategic points lead to disproportionate results.     

Testosterone,growth and the evolution of sexual size dimorphism

The integration of macroevolutionary pattern with developmental mechanism presents an outstanding challenge for studies of phenotypic evolution. Here, we use a combination of experimental and comparative data to test whether evolutionary shifts in the direction of sexual size dimorphism (SSD) correspond to underlying changes in the endocrine regulation of growth. First, we combine captive breeding studies with mark‐recapture data to show that male‐biased SSD develops in the brown anole lizard (Anolis sagrei) because males grow significantly faster than females as juveniles and adults. We then use castration surgeries and testosterone implants to show that castration inhibits, and testosterone stimulates, male growth. We conclude by reviewing published testosterone manipulations in other squamate reptiles in the context of evolutionary patterns in SSD. Collectively, these studies reveal that the evolution of SSD has been accompanied by underlying changes in the effect of testosterone on male growth, potentially facilitating the rapid evolution of SSD.