THEORIES AND PROBLEMS OF CANCER 673 



ends cover the middle of the leaf; if an individual long tentacle 

 be stimulated, only that particular tentacle moves. If an insect 

 touch one of the central tentacles, it is held by the sticky 

 substance and all the long tentacles bend over and enclose it ; 

 if an insect touch one of the long tentacles, it is also held fast 

 by the secretion and the tentacle bends over and deposits the 

 victim in the centre of the leaf, whereupon the central tentacles 

 are stimulated and so all the other peripheral tentacles bend over 

 and enclose the insect. When the prey has been secured, the 

 glands proceed to secrete a ferment that digests the insect and 

 the products are absorbed by the leaf. This is a far more 

 complicated phenomenon than the turning to the light by 

 parts of a plant but both are apparently the reaction either 

 of the individual as a whole or of parts of the individual to 

 stimulus. It is difficult to avoid the conclusion that, as there 

 is an almost insensible gradation between such phenomena 

 as these and the co-ordinate actions of man, all are connected 

 in some way and are derived primarily from some common 

 potentiality inherent in living matter when it is in the form 

 of multicellular organisms. 



When we pass from the multicellular to the unicellular forms, 

 we realise that the cells of the multicellular organism possess a 

 power quite different from any possessed by the unicellular 

 forms, that of reacting in concert. Here again we find no real 

 gap, colonial forms of unicellular animals providing the necessary 

 links. In some unicellular animals, the individuals are attached 

 to the ends of the branches of a common stalk ; each individual 

 is really a separate and independent organism and if separated 

 from the stalk is in no way incommoded but proceeds to form a 

 new colony. In spite of this, if anything disturb an individual 

 which is still attached to the common stalk, the individual con- 

 tracts, its particular twig of the stalk contracts, the main stalk , 

 contracts, the other individuals contract and a reaction in the 

 whole colony of unicellular animals takes place though a stimulus 

 has been applied to only one or two. 



In the phenomena resulting from the application of a stimulus 

 to living matter, we have then a regular and imperceptible 

 gradation between the simplest — those observed in unicellular 

 forms— and the most complex — those observed in the higher 

 animals, including man. 



The phenomena we have considered hitherto have all been 



