52 Botanic Drugs 



Physiological action often depends upon chemical 

 constitution, but not always. Urea, strophanthin, 

 and cocaine all paralyze sensory nerve fibrils, yet 

 there is no chemical relationship whatever between 

 them. Why is it that isomeric modifications in 

 alkaloids count so heavily? The dextro variety 

 has little pharmacological action, while the laevo 

 is very active. Why is this? Again: Why are the 

 unstable chemicals, like muscarine and neurine, so 

 exceedingly toxic? The pharmacologists claim that 

 the hypophosphites are inert because they are ex- 

 creted unchanged. Perhaps so; but they may be 

 in the class with strychnine. The benzene deriva- 

 tives are still a puzzle pharmacologically, though the 

 theory of dissociation may explain discrepancies 

 to a degree. 



Pharmacology is a pure science rather than an 

 applied one, and it tells us the probabilities regard- 

 ing a drug and what its line of possible utility may 

 be. On the other hand, pharmacology is weak as 

 regards the pathology of remedies, concerning itself 

 chiefly with their physiology. McCrudden, of Bos- 

 ton, has well said, "When and how to use drugs in 

 disease is outside the province of pharmacology." 



And, while animal experimentation is most val- 

 uable, yet it has an inherent weakness. Digitalis 

 raises blood pressure in laboratory experiments 

 upon animals; yet H. C. Wood, Jr., says it does 

 not in therapeutic dosage in man. James Mac- 

 kenzie, the eminent English authority in heart 

 disease, says: "In all of our observations made at 

 Mount Vernon Hospital and London Hospital, as 

 well as those made in private practice, we have 

 only found rare instances where the blood-pressure 



