User:Jtwsaddress42/Quotes/Deuchar, Elizabeth M. 1970a

 Diffusion in Embryogenesis - A Reply to Francis Crick "Sir - As an embryologist who started work during the heyday of 'fields' and 'gradients', I suppose I ought to be grateful to Dr. Francis Crick for allowing me a nostalgic look back on these long-discredited concepts which he has now resurrected - or should I say canonized - with the double halo of his own reputation and some elegant mathematics (Nature, 225, 420; 1970).

''There is, however, one point that he appears to overlook: the extreme rarity with which sheer diffusion processes occur in living systems. Twenty years ago my better-informed colleagues told me about active transport and permeases. Ever since then, if materials diffused in and out of my experimental embryos, I have regarded that as a sign that they are dying or dead. A sheet of frozen-dried tissue, extended between source and sink, might fit Dr. Crick's formulae, but - alas - it would not differentiate!"

- Yours faithfully, Elizabeth M. Deuchar''