PRECIPITATION STRUCTURES SIMULATING ORGANIC GROWTH. 23! 



to von Weimarn all solid material, including matter in the 

 "amorphous" and colloidal states, is ultimately crystalline in 

 structure; 1 and this general conception is in conformity with the 

 more recent evidence from other departments of physics indi- 

 cating that the molecules in solid matter are oriented regularly 

 to form definite geometrical patterns (space-lattices). 2 If 

 therefore to a specific molecular structure there corresponds a 

 specific molar structure (or structure peculiar to the substance 

 in its solid state of aggregation), it follows that any specific 

 protein which is synthesized and laid down in solid form within 

 the cell, or at the cell-surface or in any other situation, will 

 necessarily produce a definite and specific type of structure dif- 

 ferent from that formed by any other protein. Such a chemical 

 synthesis would thus involve a morphological synthesis of a 

 simple kind; to the constant structure of the single molecules 

 would correspond certain constant form-characters in the larger 

 aggregates built up from these molecules. It seems clear, there- 

 fore, that if specific proteins are synthesized in any organism, and if 



Delia Valle's view that the form-characters of individual chromosomes are an 

 index of a definite microcrystalline structure is especially interesting, since in this 

 case a specific chemical composition of each chromosome would be implied by its 

 specific and constant form-characters. . Cf. Delia Valle: Archivio Zoologico Ilaliano, 

 1912, Vol. 6, p. 37; also Zeitschr. f. Chemie u. Industrie d. Kolloide, 1913, Vol. 12, 

 p. 12. 



1 Von Weimarn's observations and theoretical discussions are chiefly published 

 in Zeitschrift filr Chemie und Industrie der Kolloide, 190713, Vols. 2 13, though 

 partly in Russian journals. The work is too extensive to be summarized briefly, 

 but its experimental part consists largely in showing that all transitions between 

 typically colloidal systems of inorganic and organic compounds and definitely 

 crystalline systems may be obtained by varying the conditions of formation of 

 the compounds, e. g., the concentrations of the solutions (e. g., Ba(CNS)2 and 

 MnSO-O mixed to form the compound in question, the solubility of the latter, its 

 rate of formation, etc. In this manner the crystalline structure of gels and other 

 colloidal systems is clearly indicated. Protein gels are thus crystalline in the 

 microscopic or submicroscopic character of their solid phase, and hence possess a 

 specific inner structure. The crystalline nature of fibrin gels has recently been 

 clearly shown by Howell; cf. Amer. Joufn. Physiol., 1914, Vol. 35, p. 143, and 1916, 

 Vol. 40, p. 526. For the microcrystalline structure of inorganic precipitation- 

 membranes cf. von Weimarn, loc. cit., 1908, Vol. 2, pp. 280 seq., and photographs 

 there reproduced. 



- Cf. the papers by W. H. and W. L. Bragg on the patterns produced by the 

 diffraction of X-rays at the surfaces of crystals, indicating a space-lattice arrange- 

 ment of the atoms: Proc. Roy. Soc., 1912, Vol. 88 A, p. 428, and 1913, Vol. 89 A, 

 pp. 248, 277, 430, 468. 



