VITAL GROWTH AND CRYSTALLIZATION 45 



be used in the case of a fiber or other organic material on 

 account of the exceedingly small size of the crystalline 

 components in it. 



As we have seen, time is an important factor in the forma- 

 tion of a crystal; the more time we allow for growth, the 

 greater the crystal. The same rule holds for the develop- 

 ment of the crystalline components in living tissue, even 

 though they never develop beyond diminutive dimensions. 

 A cellulose or silk fiber (which is formed by living silk 

 worms) grows by the slow addition of one diminutive par- 

 ticle after the other, sufficient time being allowed for each 

 particle to adjust itself and take up its proper position in an 

 orderly arrangement which contains diminutive crystalline 

 components. 



It is well known that artificial fibers can be produced, for 

 instance those of artificial silk, or rayon, but the process of 

 making them is much cruder. It simply consists in forcing, 

 under pressure, the thick liquid material from which the 

 artificial fiber is made into a hardening solution where the 

 thread thus formed sets. Obviously no time is available 

 in such a process for any particles to take up the proper 

 position. As might be expected, an examination by means 

 of x-rays according to the method described above shows no 

 pattern of dots as in figure 25 ; no evidence of crystallinity 

 is found in these rayon fibers. 



SUMMARY 



The first act of our drama has presented to us a large 

 number of diversified forms which resemble some living 

 ones, yet all are built up of growing crystals and consist of 

 inorganic material. The reason for this similarity is that 

 living tissues themselves are made up of diminutive crys- 

 talline elements. The building forces are therefore similar 

 in the living and the non-living world; the growth of crystals 

 and plants and animals presents some common features. 



