640 Sergius Morgulis 
6 An abundant supply of food is favorable for the regenerat- 
ing worms in this sense that fed worms regenerate both more 
segments and longer tails than worms that are not fed. But it 
is important to notice that in fed and in starved worms alike the 
rate of regeneration varies with the level from which they regen- 
erate, in accordance with the rule given in the first clause of the 
summary. It follows from this circumstance, that food must be 
eliminated as a factor in accounting for the difference in the rates 
of regeneration at different levels. 
7 The rate of regeneration can be artificially modified es 
subjecting worms to the influence of various organic substances, 
which produce either a stimulating or a depressing effect upon 
their protoplasmic substance. 
8 Alcohol may either increase or decrease the rate of regen- 
eration depending upon the strength of the solution, whereas 
chloretone decreases the power of regeneration. 
g Atropine sulphate in certain concentrations retards regener- 
ation. 
10 Digitalin may either stimulate or retard the rate of regen- 
eration, the effect being entirely dependent upon the strength of 
the concentration. In concentrations slightly weaker than the 
probable limit of toxicity (1 : 800,000) this alkaloid produces a 
retardation, whereas in a still weaker concentration it acts stimu- 
latingly on the regenerative process; by further diluting the solu- 
tion it will be rendered quite ineffective. 
ir Strychnine sulphate invariably produces a retarding influ- 
ence upon regeneration. 
12 Pilocarpine hydrochloride either stimulates or diminishes 
the power of regeneration, depending upon the concentration. 
Solutions only slightly weaker than 1 : 800,000 (the probable 
limit of toxicity) produce a retarding effect, but with greater 
dilution (1 : 3,200,000), a distinct stimulating effect 1s produced. 
By still further dilution this substance (like digitalin), is made 
entirely ineffective. 
13 Sea-water diluted to g5 per cent or even to 80 per cent of 
its normal strength produces no apparent influence upon the 
regenerating worms, the rate of regeneration remaining practically 
