The Darwinian Revolution Revisited

The Darwinian revolution remains an acceptable phrase to describe the change in thought brought about by the theory of evolution, provided that the revolution is seen as occurring over an extended period of time. The decades from the 1790s through the 1850s are at the focus of this article. Emphasis is placed on the issue of species extinction and on generational shifts in opinion.     

The structural organization of the pathogenic protozoan Tritrichomonas foetus as seen in replicas of quick frozen,freeze-fractured and deep etched cells

Summary— The quick-freezing and freeze-etching technique was used to analyse the cytoskeleton of Tritrichomonas foetus, a pathogenic protozoan of the urogenital tract of cattle. The cytoplasm presented a network of filamentous structures interacting with each other, with the surface of the hydrogenosomes and the nuclear membrane. Two nm wide filamentous structures were found in the luminal space of the Golgi complex, connecting the two faces of each cisterna. The microtubules of the pelta-axostyle system were connected by bridges 30–40 nm long and 10 nm wide, regularly spaced with an interval of 25 nm. The costa is a structure formed by a complex array of filaments and globous structures. It seems to be connected to the recurrent flagellum through a complex network formed by 15 and 10 nm wide filaments which emerge from the peripheral region of the costa and penetrate into the surface projections of the protozoan body to which the recurrent flagellum is attached. Other filaments were seen connecting the surface of these projections with the surface of the flagellum.