INJECTED PREPARATIONS 



IO6l 



should the operator succeed in getting the lung well placed, full of 

 air, and have the heart still beating vigorously, he will see before him 

 a brilliant picture of crimson network, alive with the dance and 

 dazzle of blood-globules, in rapid chase of one another through the 

 delicate and living lace-work which lines the chamber of the lung.' 

 The position of the lungs in relation to the heart and the great 

 vascular trunks is shown in fig. 792, 6. 



Injected Preparations. Next to the circulation of the blood in 

 the living body, the varied distribution of the capillaries in its 

 several organs, as shown by 

 means of ' injections ' of colour- 

 ing matter thrown into their 

 principal vessels, is one of the 

 most interesting subjects of 

 microscopic examination. The 

 .art of making successful pre- 

 parations of this kind is one 

 in which perfection can usually 

 be attained only by long prac- 

 tice and by attention to a 

 great number of minute par- 

 ticulars ; and better specimens 



may be obtained, therefore, FIG. 793. Transverse section of small intes- 

 from those who have made it tine of rat, showing the villi in situ. 



a business to produce them 



than are likely to be prepared by amateurs for themselves. For 

 this reason no account of the process will be here offered, the minute 

 details which need to be attended to, in order to attain successful 



FIG. 794. Section of the toe of a mouse : a, a, a, tarsal bones ; 6, digital artery ; 

 c, vascular loops in the papilla? forming the thick epidermic cushion on the under 

 surface ; d, distribution of vessels in the matrix of the claw. 



results, being readily accessible elsewhere to such as desire to put it 

 in practice. 1 



1 See especially the article 'Injection' in the Micrographic Dictionary; M, 



