THE BLOOD. 39 



i inch. The contents of the disk will appear homogeneous, 

 which is a term that merely indicates an apparent absence of 

 structure. The nucleus and nucleolus should also be invisible. 

 The shape of the corpuscles is oval, and they are flattened and 

 have rounded edges, with hollowed centres, in which a promi- 

 nence is usually seen (Fig. 13). The protoplasm is the sub- 

 stance of which the disk is made ; it has a light yellow color, 

 and is dull or pellucid in appearance, much like semi-solid 

 jelly. 



Brownian and amoeboid movements. Using the same 

 method of preparation the white corpuscles or leucocytes are 

 seen to good advantage. They are much smaller than the red 

 disks (in the frog the reverse of human blood), and there is 

 wide range in size, one histologist (Klein) having described as 

 many as thirty varieties. In the interior, little dark spots are 

 sometimes seen in constant vibration. By a skilled observer they 

 are readily detected, even with a good \ inch glass. When 

 such specks are numerous the bodies are said to be granular. 

 In the newt's blood this phenomenon is usually best seen. 

 The word granule has been , applied in these cases from the 

 notion once prevalent that the little dots were molecules sus- 

 pended in a menstruum of some sort that filled the corpuscle. 

 This subject is now eliciting much study, but the movement, 

 whatever its significance may be, is called the Brownian move- 

 ment. 



Klein, who states that the newt's leucocyte is traversed by an intracellular 

 network, believes that the movement just described is due to the motion of the 

 "disintegrated network" under the stimulus of imbibed water. Under this 

 explanation the oscillatory movement in the corpuscles of the human saliva 

 would indicate death rather than life. When fluid has been withdrawn by 

 evaporation the phenomenon ceases. According to other histologists this 

 vibratile motion is an indication of vital action. 



The remarkable change in form which these corpuscles un- 

 dergo is a more positive indication of vital power in the leuco- 

 cyte. When the little body is placed under conditions which 

 imitate those of its natural state it commences to put forth 

 processes and then withdraw them, carrying on these move- 

 ments slowly, but with a certain degree of regularity. While 

 this is being accomplished the corpuscle is observed to move 

 about from place to place. 



