1884.] Secretion obtained from the Medicinal Leech. 483 



coagulate with its normal rapidity, being retarded for nine or ten 

 minutes. If the peptone solution be injected into the veins of a dog, 

 and blood withdrawn from the animal at intervals after the injection, 

 it will, if the injection be powerful enough ("3 grm. peptone to every 

 1000 grms. body weight of animal), materially affect its coagulability. 



Dr. Fano* finds that certain products of tryptic digestion also retard 

 coagulation in dogs ; but curiously enough neither digestion products 

 have any action on rabbits. It may be mentioned that when injected 

 into dogs in larger quantities the blood pressure falls, there being 

 great determination of blood to the abdomen and visceral veins ; con- 

 vulsions are observed, and the animal dies in a state of coma, the 

 blood found within the body being of course fluid. 



The coagulability of the blood produced by certain poisons is 

 altogether a question of great interest ; for instance, most snake bites 

 (the cobra is an exception) produce permanent fluidity of the blood, 

 and we know nothing either of the relation of that change to con- 

 comitant symptoms, or the specific action of the venom on the blood 

 itself. 



Now inasmuch as the extract of leech is much more powerful 

 than the peptone solution in preventing coagulation outside the 

 body, its effects when injected into the system may naturally be 

 expected to lead to striking results. 



The difficulties in obtaining a license to perform the experiments in 

 England being very great, I availed myself of an invitation from my 

 friend Professor Schmiedeberg, of Strasburg, who kindly placed his 

 laboratory at my service. It is with the greatest pleasure that I 

 remember his kindness and courtesy, I wanted nothing that his well- 

 organised laboratory contained, and to him I owe much personal 

 assistance in an attempt to isolate the active principle present in the 

 leech's pharynx. This attempt, although not as yet successful on 

 account of the great difficulty of the task, will I hope at some future 

 time be renewed with more fruitful result. 



In the following experiments the extract of leech was prepared by 

 placing the anterior part of the animal in absolute alcohol for three 

 days, then evaporating off the alcohol, grinding the leech with broken 

 glass, extracting with water and filtering. 



Experiment with a Dog weighing 5000 grms. — Blood withdrawn by 

 means of a cannula placed in the carotid artery coagulated in 3 

 minutes. 



Temperature 39 0, 3 (rectum). 



5.22 p.m. 20 cub. centims. solution of 8 leeches injected into left 

 jugular vein. 



5.25 p.m. 1 cub. centim. of blood withdrawn. It remained fluid 

 until the next morning, never completely coagulating. 



* " Archiv. fur Phys.," 1881, p. 276. 

 VOL. XXXVI. 2 L 



