74 REACTION OF CELLS 



velocity is less in the first four minutes than later 

 on, which probably depends on a kind of incubation ; 

 for the paratyphosus bacillus the irregularity seems 

 to indicate some accidental irregular influence. But 

 on the whole these reactions show such a regular 

 progress with time, that their monomolecular nature 

 is obvious. This circumstance indicates that every 

 bacterium or yeast-cell or red blood-corpuscle acts 

 as if it were a single molecule in regard to the sub- 

 stance reacting upon them. This seems from a 

 biological point of view extremely difficult to under- 

 stand. We will come back to this question later on. 



According to investigations by HARVEY, not only 

 bacteria, but even higher organisms, such as Chlamy- 

 domonas, are subject to the same regularity. He 

 determined the number of moving Chlamydomonas 

 at certain times, 5 to 25 minutes after he had added 

 hydrochloric acid in the small quantity of 0-009 P er 

 cent to the water in which the monads swam round. 

 At the beginning of the experiment this number was 

 1 13, after five minutes it had sunk to 67, after further 

 five minutes to 30, at the next observation five 

 minutes later to 14, and still five minutes later to 6. 

 The logarithm of this number as a function of the 

 time of observation is represented by a straight line 

 as the figure (Fig. 21) indicates. 



According to a quotation given by Miss H. 

 CHICK, even seeds of barley are killed by poisons 

 or hot water according to the law for monomolecular 

 processes, as shown by experiments of Miss DARWIN 

 and Professor BLACKMAN. 



