44 



first place he finds that fat is normally present in them, as a 

 simple test with Sudan III in 80 alcohol shows. This fact in 

 itself does not prove anything however ; we know that fat may 

 be derived just as well from carbohydrates or proteins as from 

 fatty food : see f.i. Chanievski 14). Moreover, Nirenstein 

 himself shows that the quantity of fat in Paramaecium increases 

 just as well after a prolonged feeding on rice-starch and on 

 albumin from eggs (Albumin aus Eiern. M e r c k), as by a fine 

 oil-suspension. 



Nirenstein however states most emphatically that he has 

 observed the digestion of fat in his animals. He studied this 

 process with egg-yolk. As long as the reaction of the vacuole 

 remains acid, the fat droplets remain unchanged; as soon as 

 alcalinity is established, the fat droplets gradually form a homo- 

 geneous solution with the ,,Vacuolenschleim". No emulsification 

 is observed, but Nirenstein believes in a hydrolysis and 

 recombination within the cell-body. Animals fed on sodium 

 oleate and glycerin deposit fat in their cells, the same thing 

 happens if Na-oleate alone is used. Sain t-Hi lair e 11 3) came 

 to conclusions of the same kind for the planarians, M e s n i 1 is 

 also one of the advocates of the hydrolysis-hypothesis in inver- 

 tebrate physiology. 



B ii t s c h 1 i however already saw, that fat-droplets are thrown 

 off just as they come in. The same observation has been made 

 also by Stanievicz 122); A. Drz. (Drzewina? v. d. H.) 33) 

 in the Revue Scientifique, abstracting this paper, seems to be of 

 the same opinion. Stanievicz has extended his experiments 

 over a large quantity of animal and vegetable oils and seems 

 to be quite careful in drawing his conclusions. He completely 

 agrees with Nirenstein as far as the ingestion of fats is 

 concerned. While however bacteria and algae, taken up at the 

 same time, are digested pretty soon, the fat-droplets remain 

 unchanged, no emulsification occurs and no hydrolysis. 



,,Apres un certain temps", he says, ,,la membrane se dissout, 

 les bacteries et les algues sont partiellement digerees, par centre, 

 les globules de graisse ne sont point alteres et apres plusieurs 

 heures sont eliminees avec des parcelles non digerees." After 

 feeding olive oil to Paramaecia, he does not find any increase 

 in fats ! 



The fact that Sudan III is decolorised in the vacuoles, does 

 not prove hydrolysis according to this author. It is probably 

 due to a reduction of the dye, some of these dyes are even 

 dissolved out of the fat and eliminated by way of the pulsating 

 vacuole. Moreover Mesnil and Mouton have shown experi- 

 mentally that a lipase is not present in Protozoa. 



After feeding of egg-yolk and of carbohydrates, he finds fat. 

 His negative results with regard to the digestion of fats and 

 these findings, force him to conclude, that the fat which is natu- 



