156 J. 0. WAKELTN BARRATT AND GEORGE ARNOLD. 



still farther obscuration of the spectra oi took place, but no 

 absorption bands appeared. 



Odour. — The blood had a faint offensive odour resembling 

 decaying grass. No distinct odour of free ammonia could be 

 detected, but on adding the blood (collected from the living 

 insect a few minutes before use) to a solution of caustic 

 potash (previously ascertained to be free from ammonia) and 

 boiling, the issuing steam readily turned neutral litmus paper 

 blue, showing the presence of an ammonium salt. 



Specific Gravity. — This was found to be TOTZ (only one 

 specimen was examined). 



Reaction. — The blood examined immediately after col- 

 lection was alkaline to litmus paper. 



Basicity and Acidity. — The blood was tested imme- 

 diately after collection, great care being taken to avoid injury 

 to viscera during collection. The reaction remained slightly 



N 

 alkaline to litmus when mixed with an equal volume of ^ 



N 

 HCl ; when an equal volume of — - HCl was added the reaction 



became neutral to litmus; when an equal volume of :^ HCl 



was added the reaction became acid. The basicity of the 



N 

 blood-plasma is therefore represented by a j- solution of 



hydrochloric acid. Since the blood had an alkaline reaction 

 its acidity could not be determined by the addition of caustic 

 potash. It is obvious that the basicity was, as in the case of 

 the blood-plasma of Dytiscus, in part due to the presence of 

 ammonium carbonate, already referred to. 



Coagulation. — No spontaneous coagulation of the blood 

 occui'red on standing. 



Composition. — The blood-plasma contained 11*6 per 

 cent, of solid matter (•43 c.c. of plasma was taken for the 

 estimation of total solids). 



The plasma contained proteid coagulable on acidifying 

 with acetic acid and boiling, but as was the case with that of 



