condition _sine qua non_ of thought. In his article on _General Physiology_, M. Durand (de Gros) in criticism of M. Ch. Richet’s article on this subject which appeared in the April number of the _Revue Philosophique_, points out that Richet in applying the term “general anatomy” to the anatomy of the tissues, and “special anatomy” to the anatomy of the organs, overlooked the fact that _generality_ and _speciality_ when used to express the two opposite sides of a science express relations of abstract, nominal extension and not real extension. Thus, by general chemistry is intended the consideration of the higher laws governing the molecular actions of bodies, the one on the other, whatever that may be, and the modes of composition which result therefrom for each of them. General physiology should be, therefore, the philosophy of the science of the functions of life, that is to say, the higher laws embracing all these various particular functions; special physiology having for its object these particular functions in what is proper to each of them and distinguishes it from the others. Physiology has reference, however, to the other animals as well as man, and also to plants, and hence the term general physiology has been applied to the physiology common to all living beings, and special physiology to that which concerns the various animal and vegetal species taken separately. But this is in reality comparative physiology, and thus positive physiologists have made a false use of the term general physiology, and have left the true general physiology unrecognised and unnamed. In conclusion, M. Durand presents his conception of “organology.”