348 



Journal of Agriculture. 



[8 June, 1908. 



THE ELEMENTS OF AXLMAL PHYSIOLOCIY. 



{Confiiined from pagi 



■) 



TT'. A. Osborne, M.B., D.Sc., Professor of Physiology and Histology, 

 Dean of the Facidty of Agriculture in the University of Melbourne. 



XI. The Blood. 



The blood is a red opaque fluid which circulates through a system 

 cf tubes called blood vessels. Its functions are — 

 I . To carry oxygen and nutriment to the tissues. 



To carry carbon dioxide and waste products from the tissues. 



To distribute heat, equalizing it through the inner organs and pre- 

 venting local or general rise of temperature. 



To carry chemical messengers or hormones from organ to organ. 



To resist the attacks of bacterial parasites and to neutralize their 

 poisons. 

 The blood consists primarilv of a straw-coloured, transparent fluid 

 called PLASMA in which are suspended structures called corpuscles. The 

 plasma occupies about two thirds of the volume of the blood and consists 

 chiefly of water namely about 90 per c-nt. Of the solids present proteins, 

 in the form of albumens and globulins make up about 8 per cent. Small 

 amounts of sugar and fat can also be detected and traces of waste matter 

 sucn as urea, uric acid, (!v;c. The mineral ingredients, constituting about 

 0.9 per cent, are made up of chlorides, phosphates and bicarbonates of 

 soda, potash, lime and magnesia. The metals with which these acids are 

 combined are present in a constant proportion, nearly the same proportion 

 that exists in sea water, and their importance is considerat>le. An organ, 

 say the heart, loop of bowel, uterus, &c., cut out of a recently-killed 

 animal, can be kept alive and maintained in an active condition for many 

 hours if a solution of these salts, in the proper proportion, is pumped 

 through its vessels. Water alone or any watery solutions containing other 

 than the correct concentration and proportion of these salts will speedily 

 cause the death of the organ. 



Fig. 49. Blood corpuscles, highly maj^nified ; R., red; W., white. 

 (After Hagemann.) 



The corpuscles are of two kinds red and white. The ked corpuscles 

 are tough, elastic discs of microscopic size. Viewed from one aspect they 



