4G 



The body-cavity of Anurida, as in all tlie lusecta, is 

 the blood-containing space in which are situated the 

 various organs of the body. It extends throughout the 

 whole length of the animal, and sends prolongations into 

 the antennae, the legs and the ventral tube. It is much 

 intersected by the fat body which occupies a large 

 proportion of its cavity in many parts of the body. The 

 body-cavity is filled with the blood of the animal, and the 

 corpuscles of the latter are noticeable everywhere 

 throughout its extent ; they are specialh' abundant in 

 the head, where the vascular and haemocoelic systems are 

 in open communication with one another. 



The blood consists of {a) the corpuscles and (h) the 

 plasma. The corpuscles are circular in outline, but at 

 times they become amoeboid and give out pseudopodia 

 (Plate III., fig. '-V^). They are practically colourless, and 

 each contains a sharply defined circular nucleus. 

 Frequently small granules are scattered through the 

 cytoplasm of the corpuscle ; they are probably of an 

 excretory nature. Claypole remarks that in aewly 

 hatched individuals the blood corpuscles contain a large 

 amount of food yolk. 



11. Excretory System. 



Unlike other insects none of the Collembola possess 

 Malpighian tubes.* The excretory function is performed 

 entirely by the fat-body, or " Exkretionsorgane," as it is 

 termed by Sommer. 



In Anurida the fat-body takes the form of irregular 

 masses of tissue distributed in various parts of the body 

 and occupying a large portion of the cavity. In the region 



* In the Thysanura IMalpighian tubes are absent in Japyx, and in 

 Campodea they are only represented by papillae (Oudemans). Among 

 the Pterygota they are also wanting in Aphides (Witlaczil). 



