14 THE ESSENTIALS OF HISTOLOGY 



LESSON IV. 

 STUDY OF THE BLOOD-CORPUSCLES OF AMPHIBIA. 



1. MOUNT a drop of newt's blood obtained from the cut end of the tail. 

 Examine with the high power. Notice the shape of the coloured corpuscles, 

 both when seen flat and edgeways, and the nucleus within each. 



Measure ten corpuscles, and from the results obtain the average dimen- 

 sions of the newt's blood-corpuscle. 



Notice also the colourless corpuscles, smaller than the red, but consider- 

 ably larger than the pale corpuscles of human blood, although otherwise re- 

 sembling these. 



Sketch two or three red corpuscles and as many white. 



Be careful not to mistake the liberated nuclei of crushed red corpuscles 

 for pale corpuscles. 



Enormous cells and nuclei belonging to the cutaneous glands as well as 

 the granular secretion of those glands may be present in this preparation. 



2. Apply a drop of water to the edge of the cover-glass of the same pre- 

 paration and notice its action upon the corpuscles. 



Sketch two or three corpuscles altered by the action of the water. 



3. Mount another drop of blood, and apply dilute acetic acid (1 per cent.) 

 instead of water at the edge of the cover-glass. Make sketches showing the 

 effect of the acid upon both red and white corpuscles. 



4. Examine the corpuscles of newt's blood which has been allowed to 

 flow into boracic acid solution (2 per cent.). Notice the effect produced upon 

 the coloured corpuscles. Sketch one or two. 



The coloured blood-corpuscles of amphibia (fig. 13) , as well as of most 

 vertebrates below mammals, are biconvex elliptical disks, considerably 

 larger than the biconcave circular disks of mammals. 1 In addition to 

 the coloured body of the corpuscle, which consists, as in mammals, of 

 haemoglobin and stroma, there is a colourless nucleus, also of an ellip- 

 tical shape, but easily becoming globular, especially if liberated by any 

 means from the corpuscle. The nucleus resembles that of other cells 

 in structure, being bounded by a membrane, and having a network of 

 filaments traversing its interior (fig. 14). It is not very distinct in 

 the unaltered corpuscle, but is brought clearly into view by the action 



1 The following are the dimensions in parts of a millimeter of some of the 

 corpuscles of oviparous vertebrates : 



Long diameter Short diameter 



Pigeon . . . 0-0147 0-0065 



Frog . 

 Newt . 

 Proteus 

 Amphiuma 



0-0223 0-0157 



0-0293 0-0195 



0-058 0-035 



0-077 0-046 



