166 



Gust. Alsterberg 



F. This brings us to the question of the interpretation of the respiratory 

 curve in respect of the latter's origin. By mud-level experiments, in which I put 

 the animals in tubes that had been rilled with mud to different levels, variations 

 were obtained in the curve which allow us to draw a number of important conclu- 

 sions in this connection. 



1) The variations in the curve under these conditions are due to the diffusion 

 of 0 2 , for the stagnant water in a high and narrow tube-mouth becomes poor in 0 2 . 



2) The animals in the cultures (tube with mud -(- 1 animal) with a high tube- 

 mouth must therefore react at an early stage agaiust a lower 0 2 concentration than 

 that which generally prevails in the vessel. 



3) It is thus obvious that also with respect to the broad-filled cultures, which 

 were otherwise employed in the investigation of the respiratory curve, diffusion of 0 2 

 — which is by no means excluded by the broad-filling method, but only modified — 

 must in some way or other affect in a decisive manner the reactions of the animals. 



4) It cannot therefore be considered that there exists any »normal» respiratory 

 curve, but each curve is typical solely for the special conditions under which the 

 experiment is conducted. 



5) Thus it is assumable that it is the diffusion of 0 2 that forms the cecological 

 bounds for the reactions of the animals. 



G. Consequently we must make a number of theoretical calculations of the 

 0 2 diffusion, based on Kick's formula, such as this diffusion must have been 

 approximately realized in the water change experiments. We then find: — 



1) That in a respiratory respect the changes in the water at the bottom are 

 by no means unequivocally illustrated by analyses of the prevalent 0 2 concentrations, 

 as the changes at the bottom proceed along another track. 



2) That we must bear in mind that in the water immediately above the 

 0 2 -free mud, heterogeneous layers of water in respect of 0 2 are formed. 



3) That when there is a high general concentration' of 0 2 , these layers must 

 lie tightly collected at the surface of the mud, thus a micro-layerformation. 



4) That when the general 0 2 concentration approximates the 0 2 concentrations 

 of the respective layers, the latter must draw themselves apart from one another 

 and from the surface of the mud. The consequence will be an approach or even 

 a complete transition to macro-layers. 



5) That if we follow the course of a definite layer, we find that in the 

 presence of high general 0 2 concentration, the layer in question must wander for 

 a very short stretch over the mud, in order to wander in the same time a far 

 longer stretch when the concentration of 0 2 is low, and, finally, that when the 

 water receives addition from the 0 2 concentration of the layer in question, the 

 latter moves with the greatest rapidity. 



H. With respect to this deduction I am inclined to assume: — 



1) That by their reactions the animals follow a water-layer that is fixed in 

 respect of 0 2 concentration — a respiratory layer. 



