go A SCIENTIFIC APPROACH 



or tripotassium phosphate. Semipermeable membranes of 

 calcium carbonate or calcium phosphate were thus produced 

 and these formed osmotic globules (Figs. 6 and 7). 



Leduc considered that his experiments might form the 

 basis for a new trend in biology. He called this ' synthetic 

 biology ' : the science of obtaining living forms from lifeless 

 materials in the laboratory. He set out not so much to eluci- 

 date the physical forces underlying the phenomena which 

 were produced, as to attempt to endow his models with a 

 greater superficial resemblance to living organisms by the 

 use of very complicated procedures, some no more than hocus 

 pocus. Certainly his ' osmotic fungi and algae ' looked 

 remarkably like the corresponding living objects. But how 

 does this really help us to understand life? 



The resemblance between the objects created by Leduc 

 and living things was no greater than the resemblance 

 between a living person and a marble statue of him, and 

 nobody ever set much store by the animation of Galatea or 

 the visit of the ' Stone Guest '.* 



The work emanating from the laboratory of the Mexican 

 investigator A. L. Herrera^^ was of the same nature. In the 

 preparation of his structures, this author used somewhat 

 different materials from those used by Leduc. He mixed 

 solutions of thiocyanates with solutions of formalin. This 

 led to the formation of nitrogen-containing substances of 

 high molecular w^eight giving colloidal solutions. When 

 these were fixed with formalin or alcohol, precipitation took 

 place and quite complicated structures were formed. In the 

 course of many decades Herrera made thousands of prepara- 

 tions of these structures, some of which showed a remarkable 

 resemblance to those formed on the fixation of cells. (I have 

 been able to satisfy myself personally that this is so by examin- 

 ing preparations sent to me by the author.) Herrera also 

 described his experiments in bulletins specially published 

 by him in which he also gave numerous sketches of the 

 structures which he obtained (Fig. 8).^^ 



The interest of these studies lies in the fact that they 

 demonstrate what different forms colloidal substances can 



* The reference is to A. S. Pushkin's work of this name: cf. II Commendatore 

 in the opera Don Giovanni — Author, 



