A STUDY OF THE BLOOD OF CEKTAIX COLEOPTEEA. 151 



tosis. The latter were divided into — small non-grauular, large 

 hyaline, small granular, large granular and chloragogen cells, 

 and also spindle cells. 



Some interesting observations were made by Benham (7, 

 1901) on the coelomic fluid of Acanthodrilids, which was 

 found to undergo a sort of coagulation on standing, becoming 

 white, sticky, and slimy. The cellular elements of the 

 coelomic fluid are divisible according to Benham into four 

 groups; amoebocytes (granular cells), eleocytes (containing 

 fatty globules), lamprocytes (containing granules), and lino- 

 cytes (containing threads). 



HoUande (8, 1909) divides the cellular elements of Coleoptera 

 into three groups : h'mphocytes, granular leucocytes, and 

 leucocytes with spherules. 



The Coleoptera selected for the present investigation have 

 beenHydrophilus piceus (Linn.) and Dytiscus margin, 

 alis (Linn.). 



Mode of Collectixg Blood. 



In order to obtain blood from Hydrophilus and Dytiscus 

 the following procedure was adopted. The wing cases were 

 lifted up and pinned aside in a paraffin dish. The wings 

 were then divided with scissors, so as to display the dorsal 

 segments of the abdomen. One of the dorsal segments was 

 next opened at the side and a flap of chitin cut off iifter being 

 previously freed from adherent connective tissue. The blood 

 which Avas seen lying in the body cavity between the viscera 

 was then removed drop by drop by means of a capillary tube- 

 If this is carefully done it should be possible to Avithdraw 

 blood without damaging any organ or setting free any cells 

 derived from the body tissues. 



General Charactees of the Blood of Dytiscus and 

 Hydrophilus. 



The average amount of blood obtainable from Hydro- 

 philus piceus was ••32 c.c. The amount of blood obtained 



