312 



racteristic property of the extract, the power of preventiug the 

 clotting of blood , I thiuk it most probable that the nucleopro- 

 teid is in fact the active principle of the extract. But I believe 

 on has to delay an accurate chemical investigation till there 

 is found a method to prepare the nucleoproteid more purely. It 

 seems necessary to remove the skin of the leeches before the ex- 

 traction. It is not advantageous to extract with water, without 

 fornierly treatiug with alcohol. 



As I described pg. 303, the granules which fill the uuicellular 

 glands and their excretory ducts, swell in Na Cl 0,5 °/o, and be- 

 come clear globules , which become opaque by a very small quantity 

 of acetic acid, and are readily solved in an excess of this acid. 



So it seems not improbable that the nucleoproteid of the leech- 

 extract is derived from the granules of the glands , that thus 

 the protoplasma of the glandularcells secretes a nucleoproteid in 

 granular form, which in the moment the leech bites, flowing be- 

 tween the teeth, instantly impreguates the wound, and prevents 

 there the conglutination of the bloodtablets , and which , poured 

 out in the buccal cavity during the act of sucking , here prevents 

 the coagulation of the blood. 



