326 Report S.A.A. Advancement of Science. 



" After-effects are nut transmitted, and compared with this tact 

 hut httle importance can he attached to the use of vague analogies 

 by Detmer, who would wish to conclude that heredity is only the 

 after-effect of jirocesses which had been set going in the parent 

 organism." 



The statement that " after-effects are not transmitted seems to 

 be an extremeh rash one for a scientific man to make. It is pro- 

 verbially difficult to prove a negative, and the experimental evidence 

 at our command certainly cannot warrant such a wide generalization. 

 On the other hand, it is no doubt equally impossible at present to 

 prove experimentally that after-effects are transmitted. This is a 

 point on which we ma\ hope for experimental evidence in the future. 

 Jn the meantime we must content ourself with trying to answer the 

 question whether there is any a priori reason why after-effects shf)uld 

 not be inherited, or vice versa. We have seen already that stimuli 

 mav be stored up in the iiidividual. We shall see later on that 

 stimuli ma\ be transferred from one cell to another without the trans- 

 ference of material particles, and therefore there appears to be no 

 inherent tmprobabilitv in the view that the stimuli which give rise 

 to after-effects in the individual soma may alsf) be transmitted to 

 and stored up in the germ-cells, and give rise to after-effects in sul)- 

 sequent generations. This, of course, involves the supposition that 

 the germ-cells are ca]>able of lieing influenced bv the soma, a belief 

 which a))pears to me to admit of verv little doubt. To this point we 

 shall return later on. 



3. THK \ATLRK Ol' THE AITARATLS l!V WHICH STLM- 

 LLl ARK STORED WITHLX THE ORGANISM AND 

 THE PR1.\C1IT,E OE EQLTLIHRA TK )\ BETWEEN 

 THE CEJJ. AND ITS \TTT.ErS. 



Granting, then, as we safe!) ma\, that the organism has the 

 power ot storing up stimuli or impulses for iulure use. we are 

 naturally led to enquire whether this function is generally distriliuted 

 throughout the organism or is localised in definite cenire.s. 



This is a question which, owing to the imperfect state of our 

 knowledge, can at present only be as.sumed in a tentative manner. One 

 of the fundamental properties of living protoplasm is its capacitv for 

 responding to stimuli, or, in other words, its "irritability""; but the 

 resjjonse. as when a muscle is stimulated b\ electric shock, or an 

 Amaha puts forth envelojnng arms of protoplasm on coming in contact 

 with a food particle, generally takes place immediately or after an 

 extremely short interval, and ceases on the removal of the stimulus. 

 Protoplasm, however, also' exhibits so-called automatic move- 

 ments, i.e.. movements which do not ap})ear to be related to any 

 stimulus external to itself, and there are grounds for believing that 

 such movements are initiated and controlled bv the cell-nucleus. 



