( 42 ) 



widely accepted, as if acids could have the power of 1 liberating 

 trypsin from trvpsiiiogen is iiol correct ; on tiie coJiti-ary, they prevent 

 this liberation. 



2) That Heidknhaln came to this conclusion must he ascribed to 

 the accidental occurrence, that instead of using the j)ressed out juice 

 or wateiy extracts of the pancreas, he had taken glycerin-extracts 

 from the gland. The favorable action caused by liie presence of 

 acetic acid in his experiments ami which I have been able to c(»ntii-m, 

 is to l)e asci-ibed to the fact that acetic acid decreases the injurious 

 action of the glycerin on I lie liberation. 



3) As it has now been proved tliat the gastric juice does in no 

 wise further the lil)eration of trypsin, Itnt ratiier opposes it, we may 

 therefore draw the conclusion, Ihat hi f/a's jinx-i'ss of liJx'rotion all 

 tlic irork fiills III thi' iiifcsiiiidl jnirf; n fitvt stil 'nirriuisiiKj in iiii- 

 porfimcf' irlii'iu' tlw iiiri'stbjutlons of Popiet-ski hare pivn-d, that no 

 fnu' inipshi irlntti'rct' ajtpem's in tin' imncn'Kssi'crt'ta, hut that it is 

 onhi tlii'rt' in the .s/nijji' of trmisinLxjen. 



Having arrived at the end of my communication, I beg Prof. 

 llAMBUiUiKK to accept my warm thanks for the oppoi-tunity allorded 

 to me to make these researches and also for the useful hijits kindly 

 gi\en to me. 



lyn/sio/ot/iciil hihoriitorji of tin' Stntr I 'iiircrsitij itt 

 Livnniiiijrn. ^(^11 JlMI.'j. 



Physics. — "■Some remai'ls on tin' rpri'i'sihilitij of nioh'nilir motions." 

 iiy ])r. A. Pannekokk. (Communicated by Prof. H. A. Lokkntz). 



1. The following considerations deal chielly with the ijuestion 

 whether a mechanical explanation of nature is possible. Mechanics 

 treat the motion of discrete particles or of continuous masses; now 

 the question may l»e raised, whether all natural phenomena can l)e 

 explained by means of such a motion. 1ji other words, it is the 

 (jnestion, whether oi' no we know particular properties of these }»heno- 

 mena, ^^ hich exclude the possibility of a mechaiucal explanation of 

 general applicatio]i. A })articnlar propei-ty Avhich seems to do so, is 

 the irreversibility of the natural phenomena, the change in a detinite 

 direction. When investigating whether this is really the case, we need 

 only consider the simi)lest form iji which the irreversilulity of natural 

 phenomena occnrs: the second law of the mechanical theory of heat. 



