64 Can Science Explain Life? 



This can take place only during the resting stage. 

 Although such a folding over has never been ob- 

 served, yet there seems to be no other way of ex- 

 plaining the replacement of germinal material if 

 the spirazines extend lengthwise of the chromo- 

 somes, and a similar process is exhibited by the 

 pairing of homologous paternal and maternal 

 chromosomes during synapsis. 



In several cases there has been observed a deli- 

 cately coiled basichromatic thread, known as the 

 "chromonema," which occurs as a spiral winding 

 around the spireme thread and around the chro- 

 mosomes during certain stages of cell division. 

 The chromonema is always very uniform in 

 contour when it is first formed, but usually 

 straightens out and thickens or collects along 

 opposite sides just prior to longitudinal splitting 

 of the spireme thread or prophase chromosomes. 

 The fact that it stands out conspicuously in 

 stained preparations does not prove, however, 

 that it plays an important part in vital processes. 

 Its affinity for stains may be due to nucleic acids 

 or other purine or pyrimidine derivatives in a 

 molecular state of dispersion which may have 

 been formed as suggested in Fig. 9 by lateral 

 compression of the spirazine complexes in one 

 direction or another. Although its contents may 



