CAPILLARIES. 



691 



Capillaries are, with very few exceptions, always sup- 

 ported by an areolar network, which serves not only as an 

 investment to them, but connects them intimately with 

 the tissues they are destined to supply. A possibility 

 arises, in first examinations, of mistaking or confounding 

 capillaries with nerves, 

 especially if the part 

 under observation should 

 have been left for some 

 time in strong preserving 

 or alkaline solutions. 



A weak solution of 

 caustic soda, and also 

 another of acetic acid, are 

 both of use ; the first is 

 available for the purpose 

 of tracing nerves ; the 

 latter in making out 

 vessels, structure of pa- 

 pillae, unstriped muscle, 

 &c., inasmuch as it renders 

 their nucleimore obvious ^ 319 _ m broncU> a ^ mtwork of 



while SOda thickens and air-tubes for supplying the lungs with air. 



makes them less so. It is very useful sometimes to use 

 these re-agents alternately ; the rule is, to apply them to the 

 object while under 

 the microscope, so as 

 to watch their gra- 

 dual operation. 



It is not in the 

 blood alone that cells 

 float in a fluid ; the 

 chyle and lymph are 

 colourless corpuscles 

 flowing along their 

 especially - adapted 

 tubes and ducts, and 

 carrying the nutritive 

 particles gathered 



from the food tO the Fi S- 320. A capillary of blood-vessels distributed 

 iii i * *i. to <* ft* tissue - Better seen in some of the in- 



blood- Vessels, for the jected specimens, Plate VII. 



