70 The Mickoscope. 



become perfectly useless; it has arrived at the limits of its demon- 

 strating capacity, and it delivers, without hesitation, the further 

 solution of inquiries into the hands of the spectroscope, and it is 

 just here that its analytical powers prove of the greatest importance 

 and usefulness. 



THE BLOOD. 



The blood-corpuscle is the highest developed oi'ganized cell known. 

 The chemical composition of the blood is calculated according to the 

 following formula: ^600. if 960. i\r.l54. Fe. S.^. 0.177, leading 

 to an atomic weight of 13280. Its atomic weight and complex 

 composition are the marvel of the analytical chemist. The dis- 

 covery that these blood-corpuscles contain a crystallizable substance 

 is of recent date. The first observations were made by Reinhart, 

 Koellicker and Funke, and still later by Lehman, Hoppe-Seyler, 

 and others. Lehman gave to this crystallizable albumen the name 

 of "Blutcrystalle" — blood-crystals. This physiologist was however, 

 but partially aware of the great physiological importance and func- 

 tion of these crystals, for in his "Handbook der Physiologischen 

 Chemie," he says that owing to the entire absence of knowledge 

 respecting the chemical constitution of this substance, we are unable 

 to form any opinion regarding its genesis. 



Even as recently as 1858, Rudolph Virchow did not assign to 

 these crystals any special function. He was very well aware of the 

 fact that they behaved in certain respects like organic substances, 

 inasmuch as they become larger through the action of certain 

 agencies, and smaller through that of others, without change of 

 form. He was also aware that the form of crystallization was 

 different in different animals, and he adds " that hitherto it has not 

 lieen possible to discover any satisfactory reason for their existence, 

 or to obtain any insight into the nature of their substance." 



And yet he was aware that these crystals wei'e affected hj 

 oxygen and carbonic acid precisely as the blood is; that thej 

 became of a bright red color with oxygen, and dark and bluish red 

 with carbonic acid In common with the former erroneous views of 

 writers upon this subject, the coloring pigment of the blood, " Der 

 Blutfarbestoff," was described by him as haematine, yet Lehman 

 had already shown that this insoluble substance, so rich in ii*on, 

 is not found as such in the blood, but that this haematine is in 

 reality a product of decomposition of the true pigment of the 

 blood, which is now known and designated as Haemoglobin, Haemato- 

 crystalline and Cruorine. 



