40 



MANUAL OF HISTOLOGY. 



Pio. 15. Leucocytes: a, putting out pro- 

 sses ; ft, having withdrawn them. (Hollett.) 



In Fig. 15 the leucocytes are seen. Those marked with the 

 letter a are engaged in amoeboid motion. The one marked b 

 i? in a state of contraction. . This phenomenon is called amoe- 

 boid movement, because it resem- 

 bles that of the amceba the lit- 

 tle microscopic organism found 

 in stagnant water. In order to 

 permit these changes to continue 

 for some length of time, it is well 

 to paint a little oil or glycerine 

 around the edge of the circle. 

 Evaporation is thus prevented. 



If the warm slide be used the 

 changes will follow with greater 

 rapidity. Both Brownian and 

 amo3boid movements are usually confined to a limited number 

 of the corpuscles, and the former often to only a small portion 

 of the interior. 



The slide ' for heating consists of an ordinary glass slide 

 (Fig. 16) upon which is riveted a thin copper plate (b) perfor- 

 ated in the centre, so as to allow space for the drop of blood 

 which is to be examined. From the copper plate extends an 

 arm (c) over which is slipped a spiral copper wire (e), which is 

 heated by the flame of an alcohol lamp. By this means the 

 glass plate is kept warm and with it the drop of blood. In 

 order to secure a proper 

 amount of heat.and no 

 more, it is customary 

 to put a little bit of 

 cocoa butter upon the 

 corner of the slide. The 

 butter melts at the tem- 

 perature of the body, 

 and after this point has 

 been reached the lamp 

 should be carried along 

 the wire away from the slide until the precise distance is found 

 at which this particular degree of heat will be maintained. 

 Action of a dilute salt solution. It is often difficult, and, 



FIG. 16. Slide for heating : a, slide; 6, copper plate ; c, arm 

 over which the spiral wire (<f ) is slipped 



1 Made by T. H. McAllister, 49 Nassau Street, New York City. 



