260 THE INDUCTIONS OF BIOLOGY. 



minous substance : probably a combination of various pro- 

 teids. And the evidence, as summarised by Wilson, seems 

 to show that where the proportion of phosphorized acid is 

 high the activity of the substance is great, as in the heads of 

 spermatozoa; while, conversely, where the quantity of phos- 

 phorus is relatively small, the substance approximates in 

 character to the cytoplasm. Now (like sulphur, present in 

 the albuminoid base), phosphorus is an element which, 

 besides having several allotropic forms, has a great affinity 

 for oxygen; and an organic compound into which it enters, 

 beyond the instability otherwise caused, has a special insta- 

 bility caused by its presence. The tendency to undergo 

 change will therefore be great when the proportion of the 

 phosphorized component is great. Hence the statement that 

 " the chemical differences between chromatin and cytoplasm, 

 striking and constant as they are, are differences of degree 

 only; " and the conclusion that the activity of the chromatin 

 is specially associated with the phosphorus.* 



What, now, are the implications? Molecular agitation 

 results from decompositon of each phosphorized molecule: 

 shocks are continually propagated around. From the chro- 

 matin, units of which are thus ever falling into stabler states, 

 there are ever being diffused waves of molecular motion, 

 setting up molecular changes in the cytoplasm. The chro- 

 matin stands towards the other contents of the cell in the 

 same relation that a nerve-element stands to any element of 



* While the proof was in my hands there was published in Sdence Pro- 

 gress an essay by Dr. T. G. Brodie on " The Phosphorus-containing Substances 

 of the Cell." In this essay it is pointed out that ' nucleic acid is particu- 

 larly characterized by its instability ... In the process of purification it is 

 extremely liable to decompose, with the result that it loses a considerable part 

 of its phosphorus. In the second place it is most easily split up in another 

 manner in which it loses a considerable part of its nitrogen ... To avoid the 

 latter source of error he [Miescher] found that it was necessary to keep the 

 temperature of all solutions down to C., the whole time of the preparation." 

 These facts tend strongly to verify the hypothesis that the nucleus is a source 

 of perpetual molecular disturbance not a regulating centre but a stimulating 

 centre. 



