Boyal MicrosGOjpical Society. 65 



which is observed in the properties of the colourless blood corpuscles, 

 stands probably — especially in regard to their size— in a certain 

 relation to the diiferent stages of development in which they are 

 found ; but, in regard to the amoeboid movements, they may also 

 partially depend on the constitution of the blood itself. Thus, for 

 instance, did I find these amoeboid movements of the colourless 

 corpuscles in the fresh blood of a boy, thirteen years old, only to 

 begin after the addition of water, while in the blood taken from the 

 arm of a woman, thirty years old, they manifested themselves almost 

 immediately, and very actively. In the blood of another woman, 

 twenty-two years of age, taken from the os uteri at the beginning 

 of menstruation, and examined immediately, and in which the 

 colourless blood corpuscles were but sparsely represented, and not 

 much larger in diameter than the colom'ed, the movements mani- 

 fested themselves immediately. In a similar manner they appeared 

 differently in a number of other cases, sometimes even in the blood 

 of the same individual, when it was examined at different times. 

 The most active movements of the colourless blood corpuscles I 

 observed in the blood of a man who fell a victim to the bite of a 

 water -moccassin (Triconocejplialus piscivorus). It was taken from 

 a vein one hour and a half after death, and examined one horn' later. 

 The processes which issued from the mass of the bodies of the 

 corpuscles presented the most variegated forms ; equally as active 

 was the dancing molecular movement of the dark-bordered granules. 

 The addition of water affected the movements in no way. One hour 

 later, the dancing movement of the granules was found to have 

 ceased, while the amoeboid movement of the layer of protoplasm 

 was still going on. 



Let us now ask the question : What do these amoeboid move- 

 ments, observed in the colourless blood corpuscles, signify ? And, 

 furthermore, do they take place while the latter are carried along 

 by the blood in active cu'culation, or is an abnonnal stimulus 

 requisite for their production ? The direct observations, regarding 

 the passage of these corpuscles through the walls of the finer blood- 

 vessels, were made on inflamed tissues, at a time when the nutrition 

 of the latter was deranged, and when, in consequence, they were 

 performing their general functions under abnormal conditions. The 

 facts elicited by these observations, therefore, would not be sufii- 

 ciently conclusive to presume that the movements through which 

 the colourless blood corpuscles pass through the walls of the blood- 

 vessels also occur while these bodies are circulating through the 

 vessels of a tissue or organ in a normal state. Further observations 

 made by several observers, however, have shown that some kind 

 of organic cells really possess the capacity of passing by means of 

 amoeboid movements from one locality to another. The question 

 whether these movements are due to an inherent property of the 



