71 



The material penetrated into the very tip of the ..livers" ; a small 

 piece of the tip of one of these organs was dissolved in nitric 

 acid and gave a strongly positive prussian-blue reaction. When 

 one has actually seen an experiment of this kind, one imme- 

 diately realises the importance of the radial sacs as organs of 

 resorption. 



The fixed material was cut up in Amsterdam where Mr. 

 K. B o e d y n obliged me very much by his valuable and expe- 

 rienced help. It appeared that up into the smallest ramifications 

 of the radial sacs little iron particles could be seen, which can 

 easily be made visible as blue grains -prussian-blue- by a 

 treatment of the sections with ferro-cyanide and hydrochloric 

 acid, described by Tartakowsky 126) '). But this is not the 

 only thing visible in these sections. In fig. 5 of our plate, we 

 see one of these sections in its natural colors, resulting from a 

 combined treatment with eosin and the prussian-blue procedure. 

 In this figure we also see that the material is actually resorbed. 

 The cuticula of many cells shows a dark blue coloration, 

 the iron seeming to diffuse out into the gut epithelium. Then we 

 can not foUow it any more tiU we see it again in the pavement 

 endothelium of the coelomic cavity. This layer has in some 

 sections a very dark blue color. No considerable quantities of 

 iron are found in the layer of connective tissue, but the coelomic 

 endothelium, the „stain-layer", seems to store the materials which 

 have been resorbed. before giving them off to the perivisceral 

 fluid. 



Something of the same nature could be observed in some 

 experiments in which a solution of ammonium carminate was 

 injected. On dissection the radial sacs of such animals appeared 

 to be absolutely red. They were fixed in alcohol, in which, 

 as we know, ammonium carminate is insoluble. They could in 

 that way be passed through xylol and paraffin without fear 

 that the stain would be dissolved. In these sections one of which 

 has been pictured in fig. 6 of our plate, we again see something 

 of the same nature. The carminate has been resorbed by the 

 epithelium and passed over to the ..membrane nutritive", as 

 Cuenot has called an analogous layer in other forms. It is 

 seen here not only in the coelomic endothelium, but also in the 

 layer of connective tissue. Unfortunately these radial sacs were 

 taken out at a late stage of the resorption. The actual 

 resorption process can not be observed as in the iron 

 sections, but the result is as clear as it could possibly be. The 

 presence of the carminate everywhere in the coelomic lining 

 investing the radial sacs, is the most conclusive proof that 

 these organs have resorbed it. 



1) The sections, after having been freed from paraffin and xylol, were 

 put into a iVs'/o solution of potassium ferro-cyanide for 15 minutes, then for 10 

 min. into a 0.45 "/o HCI solution. 



