^98 



When the ligamentum nuchae is eaten by a dog and the animal 

 killed several hours later, it will be found that the thick elastic fibrils 

 have at many points begun to be dissolved. The ends of the fibrils 

 have, often for quite a distance, fully been dissolved with the ex- 

 ception of an enveloping membrane which tinges with picro- carmine. 

 The same membrane can be demonstrated by digesting yellow elastic 

 tissue with boiling KOH or with boiling concentrated HCl. The pre- 

 paration must, of course, be carefully watched or else the whole elastic 

 tissue will be dissolved. Just as the specimen is becoming transparent 

 it is to be thrown into water in order to prevent further destruction of 

 the tissue. In successful preparations made in this way nothing but 

 the membranes remain. 



Also by digesting aseptic or sterilized tissues with the spirillum 

 of FiNKLER-PßiOR or the bacillus of green pus beautiful preparations of 

 the membranes may be obtained. The best preparations were obtained 

 by allowing Finkler-Peior's spirillum to act upon the tissue at ordi- 

 nary the room temperature for two mouths. Many other organisms 

 (prodigiosus, anthrax, Denecke's spirillum, Booker's bacillus A and 

 putrefaction organisms) do not seem to aflect the elastic fibrils, even 

 after months. 



The most satisfactory method of demonstrating the membranes 

 of elastic fibrils is to digest the tissue with the vegetable ferment 

 known as papoid. This ferment will, in slightly acid or alkaline 

 solutions, at 31^ C, in a few hours (5 to 20), dissolve all the interior 

 of the fibrils and leave nothing but the membranes^). The membranes 

 are not affected by either acid or alkali. 



White fibrous tissue is not digested by papoid, and when once 

 treated with it responds in the same manner as fresh tissue to either 

 acid or alkali. Absolutely definete preparations of the membranes are 

 made by treating a large piece of elastic tissue with strong acetic 

 acid for days, then thoroughly washing with water and then digesting 

 one end of the ligament with papoid. The digested end has lost its 

 elasticity and appears much like white fibrous tissue. Nothing but the 

 membranes remain; they may be preserved in concentrated acetic acid. 



The interior of the elastic fibril is composed of a highly refractive 

 substance, viz. elastin, which when digested first breaks up into ir- 



1) During papoid digestion a great many large bacilli grow in the 

 preparations. Papoid contains almost a pure culture of bacilli which, to 

 a certain extent, digest elastic fibrils. Still the rapidity in which papoid 

 dissolves elastin can not be accounted for by the papoid bacillus, for pure 

 cultures of the bacillus by no means digest elastin so rapidly as the papoid. 



