112 



under the microscope in an artificial serum, while the or- 

 dinary animal temperature was preserved as well as pos- 

 sible. But the mesentery of the frog has been found to 

 furnish the best opportunity to watch their movements, 

 and revealed very novel and startling facts concerning 

 their behavior. Here they have been seen to take 

 granular pigment, purposely injected into the veins, into 

 the interior of their bodies, and after bearing it to a 

 greater or less distance through the circulation, to again 

 eject it. Or they have been seen to pass through minute 

 apertures in the capillaries bearing the pigment with them 

 into the surrounding tissues. Owing to these free move- 

 ments they have been called wandering cells. They sug- 

 gest an explanation of the agency by means of which 

 diseased action in one portion of the system is sometimes 

 transferred to remote portions of the human frame. It 

 would be impossible to ascertain these facts from an ex- 

 amination of the opaque tissues of the body. Yet they 

 are of immense practical importance. Hence it is a phi- 

 lanthropic work to study the tissues of the smaller ani- 

 mals by means of which such information is obtained. 



It has been recenjiy suggested that the Society for the 

 Prevention of Cruelty to Animals should make exertions 

 to put an end to physiological experiments upon the 

 lower animals. Such action will be deprecated by all 

 who Avould act for the prevention of cruelty to men. 

 For such experiments are still necessary to furnish the 

 knowledge requisite to proper action for the relief of 

 human suffering. 



