69 



A. If in nature such a sponge containing an arbitrary number 

 of green algae and growing in light — for its green algae 

 then we have i -\- r -\- mii = e -]- f/ -\- mo (I) — is transported into 

 darkness, what is going to happen then? The multiplication of 

 the green algae must then become much smaller (= + 0), the 

 mortality much more intensive ; while the import remains the 

 same, also the export (at least in the beginning), but the growth 

 of the sponge will probably decrease immediately and the reduc- 

 tion remains the same (= 0). The original equation i -\- r + >}iu = 

 e -\- g -\- mo passes into i -\- r -\- niii < ^ + 5' + ^^^^ (H)* The ba- 

 lance is broken, the sponge must continually lose green algae, 

 therefore become more and more colourless. In consequence of 

 this decrease of the concentration of green algae the import, the 

 reduction and the multiplication do not change, the mortality how- 

 ever decreases as well as the export, while also the factor of growth 

 will be diminished ; but the formula i + r -\- mu < e + ^ + >no 

 remains binding (III). Consequently, the end of this process must 

 be that all green algae disappear from the sponge tissues, the 

 sponge itself becoming perfectly colourless. Then, of course, 

 also the second part of the formula e + ^ + ^no must decrease 

 automatically till it has become equal to i + r + ww, so till a 

 balance i + >' ~\- nm = e + g -\- mo is re-established (IV) ; but now 

 another than the original one. So the mortality must have dimi- 

 nished ; nevertheless it is then still strenger than in the begin- 

 ning (p. 59), and rather considerable. When this state of per- 

 fectly colourless sponge in darkness is reached, the import is 

 still rather considerable, the factor of growth has diminished 

 still more and the multiplication, the reduction, and the export 

 are + 0. In stead of i -\- r -{- mu = e ^ g -\- mo we may put 

 i = g -\- mo ; in fact even / = mo. In other words, in such a 

 colourless sponge in darkness the whole import is always counter- 

 balanced by the mortality (and the growth). 



We may symbolize the transition mentioned, in the fol- 

 lowing way: 



