40 BEES AND BEE-KEEPING. 



The blood of the bee is colourless, and contains 

 but few corpuscles, which are always white, and 

 carry a nucleus surrounded by granular matter, and 

 have the wonderful though not unusual quality of 

 constantly changing their outline, whence they are 

 called amoeboid. At one moment they will be round, 

 but slowly they become ellipsoid, and then, perhaps, 

 an irregular boat shape, or even star-formed. 



Our subject is so vast that space can hardly be 

 spared for the discussion of exploded theories; but 

 some mention must be made of the so-called "peri- 

 tracheal circulation," a pet notion with M. Emile 

 Blanchard. It was supposed that the blood was 

 carried along the tracheae, between their two walls.- 

 The idea was based upon a misunderstood experi- 

 ment, and the microscope gave no countenance to 

 it; it may now be regarded as beyond resuscitation. 

 The coup de grace was administered in Graber's 

 explanation of the functions of the diaphragm, which 

 has removed a great difficulty, as it is now seen that 

 the blood in the pericardial cavity is enriched with 

 oxygen, by the numerous fine tracheae there placed, 

 and sent in best condition into the dorsal vessel to 

 supply first the brain, and then, in turn, every part. 



The muscular system, by which all movements are 

 brought about, depends for its action upon nerve, 

 which induces a contraction, bringing nearer together 

 the parts attached to the extremities of the fibres 

 building up the muscle. The individual fibres, parts 

 of two of which are represented in Fig. 9, are very 

 varied in size in bees. The largest with which I am 

 acquainted are those forming the powerful muscles 



