A STUDY OF THE BLOOD OF CEETAIN COLEOPTERA. 157 



Dytisc US, complete, precipitation did not occur, so that a 

 quantitative estimation of the amount of coagulable proteid 

 was not possible. 



On diluting the blood with ten times its volume of distilled 

 water a copious white precipitate formed, showing- the pre- 

 sence of globulin. 



The dried solids of the plasma contained about 3 per cent, 

 of ash of a white, porous, earthy aspect. Owing to the small 

 amount of ash obtainable no determination of its composition 

 could be made. 



Osmotic Pressure. — The freezing-point of the blood- 

 plasma-, determined by Beckmann's method (1 c.c. of fluid 

 was employed), was — •647°C., corresponding to an undisso- 



ciated , solution. 



Granular Material. — This consisted of small particles, 

 exhibiting Brownian movement, "2 fx to 2 ^t, in diameter, 

 the former being the more numerous. In addition ultra- 

 microscopic particles less than '2 f.i in diameter could be 

 seen on strong illumination on a dark background. The 

 granules increased in number on standing; some of the 

 larger granules may have been derived from the disintegra- 

 tion of the blood-cells. The granules, in films fixed by 

 Flemming's solution, stained by basic dyes. 



Gases Dissolved in Blood-plasma. — By means of a 

 Toepler pump the dissolved gases contained in 1*6 c.c. of 

 blood-plasma (obtained from five Hydrophili) were collected 

 and were found to measure '09 c.c. After the absorption of 

 carbon dioxide by caustic potash the volume of gas was 

 reduced to "OS c.c. Very little further reduction could be 

 obtained by the action of pyrogallol in strongly alkaline 

 solution. The percentage of dissolved gases was therefore : 

 Carbon dioxide .... 3*8 per cent. 

 Nitrogen 1-9 ,, 



Total . . . .5-7 



