NOT DEATH-STRUGGLES 147 



causes this excitation. We have tried several alkaloids, 

 and all of them have had this effect. It does not matter 

 what the alkaloid is, nor whether it is a salt or an 

 alkaloid; the result is the same. In fact, we think 

 that it is probable that this power of exciting amoeboid 

 movements is a property of alkaloids generally. It is 

 true that we have not yet tried all known alkaloids, 

 but we have experimented with many, and we think 

 that they probably all have this effect. Moreover, the 

 parent substances of alkaloids, such as pyridine and 

 quinoline, also excite w r hite blood-corpuscles. 



Some alkaloids cause more excitation than others; 

 atropine has so far proved the most effectual, morphine 

 the least. To man atropine is very poisonous; mor- 

 phine is not so poisonous, weight for weight. To a 

 man's leucocyte, however, it is curious to note that 

 morphine is the more poisonous, and atropine not 

 nearly so dangerous. By means of this jelly method 

 we can try the effects of alkaloids and substances in 

 various strengths on leucocytes and other cells, and if 

 the jelly contains atropine, by noting the extent of the 

 excitation one can find out the dose of an alkaloid 

 which will cause maximum excitation and the dose 

 which will cause death in a given time. Generally 

 speaking, it requires three times as much of a given 

 alkaloid to cause death as it does for it to cause 

 maximum excitation. 



This latter point is an important one, for it has 

 been suggested to us that the excitation by alkaloids 

 is in the nature of a death-struggle. It is clear, 

 however, that if it was, the excitation would steadily 



