72 



Another series of injectioas was made with olive oil. This 

 substance also was seen to enter the radial sacs, which 

 looked like a kind of oily gland shortly after the injection 

 had taken place. For fear that I might dissolve away the fats 

 by passing the fixed radial sacs through the alcohols and xylol, 

 they were fixed in Flemming, washed and imbedded in soap. 

 The recent method of Mc. Junkin described in chapter 16 

 was used for this purpose. 



Also in these fat preparations the same thing could be observed 

 again. The whole epithelium appeared to be full of fat in drops 

 of all sizes. It was so full that the sections, notwithstanding the 

 fact that the Flemming had stained the fat only incompletely, 

 appeared to be dark greyish even on superficial examination. 

 The addition of Sudan III gave a most brilliant picture as 

 described in chapter 16 which one could not possibly reproduce 

 in print. The whole epithelium appeared like one mass of reddish 

 droplets. 



From all this evidence we see that without any doubt this 

 „Uver" like so many other invertebrate livers is primarily and 

 chiefly an organ of resorption. It is rather remarkable that 

 KrXikenberg 78) came to results which are absolutely con- 

 tradicting mine in experiments of the same kind. He fed Astro- 

 pecten pentacanthus and aurantiacus and Asteracanthion glacialis 

 on fibrin stained with different dyes and never saw them enter 

 into the radial sacs. He concludes: „dasz die sogenannten 

 Radialanhange des Asteridenmagens reine Ausfiihrungsgange des 

 Leberdriisen sind und dasz in sie am normalen Tier kein Speise- 

 brei gelangt." In connection with my remarks in the introduction, 

 I do not consider this as a very serious objection to my results. 

 Just as in the snails the food substances here enter into the 

 liver to be resorbed there. 



One peculiarity, however, of the snail's liver is absent here, 

 Biedermann and Moritz describe were definite and active 

 movements of the separate pouches of the Helix liver, causing 

 currents which move the food through the whole organ. They 

 compare the liver of an animal in full digestion to a kind of 

 boiling jelly, bubbling here and there. This does not occur in 

 starfishes as far as I could observe. Their radial sacs are com- 

 pletely motionless during the period of food ingestion, probably 

 the cilia do most of the work here (compare also the chapter on the 

 histology where we mentioned that muscle fibres are either 

 absent or only occasionally present in these organs). 



Nearly all natural food in starfishes seems to be digested 

 very completely. The anus is almost never used and is very narrow. 

 Shells if taken up are removed by the mouth. This also might 

 furnish evidence in favor of a very complete resorption into 

 and digestion in the radial sacs. In the other groups of Echino- 



