524 



JOHNSON. 



[Vol. VIII. 



repeated observations on this point, under conditions that 

 admitted of accurate counting of the nodes both before and 

 after regeneration, with what results the following table will 

 show : — 



Out of the 18 examples, 14, or nearly jZ per cent, show an 

 increase of nodes. In two (Nos. 3 and 5) the number remains 

 unaltered, and in two (Nos. 10 and 13) there is a decrease. 

 Sometimes the nodes are more than doubled in number (No. 4). 

 While the extent of the increase in the number of nodes is 

 highly variable, it is as a rule greatest in meganuclei with a 

 small number of nodes (Nos. i, 4, 14, 16, 17), and smallest in 

 meganuclei with an uncommonly large number (Nos. 6, 8, 9). 

 The average number of nodes for the 18 regenerated Stentors 

 is 16, while the average number for the 44 young Stentors (i.e. 

 22 pairs) given on p. 516 is only 12.6 nodes. It is possible, 

 then, to see an important function of regeneration in the 

 marked increase in the number of nodes over and above those 

 formed at time of fission; for in this way the superficial extent 

 of the nuclear substance is greatly enlarged. If the nodulation 

 of the meganucleus has a physiological value — and we can 

 hardly conceive of its being so carefully maintained unless 

 it has — it is reasonable to suppose that an increase in the 

 number of nodes, up to a certain limit, is for the advantage of 

 the organism. We have seen that the process of renodulation 

 brings about the same result, whether it occurs at time of 

 fission or at time of regeneration. The increase of nodes in 

 the former instance is for the advantage of the race, in the 

 latter for the benefit of the individual. 



