356 



ORGANIC GROWTH 



SEC. 



ments of the several portions, after having been destroyed by 

 the cuts, after a time was re-established. Communication 

 must therefore have been effected by nerves which previously 

 did not perform this function ; some nerve-fibrils must have 

 taken up the function of others, have acted vicariously in 

 place of these.^ 



Experiments on Beroe gave me similar results.^ I have 



«. 



^^. 



.?«€«^ 



A 





I 



already briefly stated that in this 

 animal also when parts are separ- 

 ated a new centre of action 

 appears in them. I now return 

 to this subject, and give a short 

 account of my experiments. 

 ~ Experiraent A. — I cut five Beroes 

 into three parts transversely so as to 

 form from each three parts of equal 

 B height, of which the upper. A, con- 

 tained the aboral pole, with the 

 largest aggregation of ganglion-cells ; 

 the lower, C, contained the mouth ; 

 while the third, B, was the middle 

 Q portion of the body. 



After the division, the movement 

 of the swimming- plates ceased com- 

 pletely in all the pieces, but re- 

 commenced after a short time in 

 all those pieces which contained 

 Shortly afterwards, movement began 

 again in those portions distinguished as B and C, but in these 

 ceased again after a time, while in the A pieces it continued. 

 When I examined the pieces again after four hours, I 



^ Cf. Die Medusen, p. 31. Romanes's results also proved the same vicarious 

 action of nerve-fibres in Medusae, Phil. Trans, vols, clxvi., clxvii. 

 2 Archiv. f. mikr. Anat. Bd. xvii. 



Fig. 4. 



an aboral sense-organ. 



