408 



TEXT-BOOK OF ENTOMOLOGY 



italicus, Saturnia pyri, Anax formosus, and others, 0.011 to 0.014mm.; of 

 EpMppiger vitium, (Edipoda ccerulescens, Pezotettix mendax, Zabrns yibbus, 

 Phryganea, and others, 0.012 to 0.022 mm.; in Stenobothrus donatus and varia- 

 bilis, 0.012 to 0.035 mm. The largest known are those of Melolontha vulyaris, 

 which measure from 0.027 to 0.03 mm. 



As regards the nature of the corpuscles, Graber concludes that they 

 are more like the cells of the fat-bodies than genuine cells. That 

 they are not true cells is shown by the fact that after remaining in 

 their normal condition a long time they finally coalesce and form 

 cords. After shrivelling, or after the blood has been subjected to 



A 



B 



FIG. 381 

 same forms 

 the nucleus 

 after a long 

 Graber. 



K 



Blood corpuscles, or leucocytes, of insects : A, a-y, of Stenobothrus dorsatus (the 

 occur in most Orthoptera and in other insects). S, a, leucocyte of the same insect with 

 brought out by ether ; >, another of serpentine shape. C, leucocytes of the same insect 

 er stay in ether. D, leucocytes of the same after being in glycerine 14 days. After 



different kinds of treatment, the nucleus is clearly brought out 

 (Fig. 381). 



Besides the blood corpuscles there have been detected in the blood 

 round bodies which are regarded as fat-cells. They are circular, and 

 for the most part larger than the blood corpuscles, have a sharp, 

 even, dark outline, and an invariably circular nucleus. (Kolbe.) 



The blood of Meloe, besides the amoeboid corpuscles, according to Cue"not, 

 contains abundant fibrinogen, which forms a clot ; a pigment (uranidine), which 

 is oxidized and precipitated when exposed to the air; a dissolved albuminoid 

 (haemoxan thine), which has both a respiratory and nutritive function ; and, 

 finally, dissolved cantharidine. 



The corpuscles arise from tissues which are very similar to the fat-bodies, 

 and which, at given times, separate into cells. The position of these tissues is 

 not always the same in different insects. In caterpillars, they occur in the 

 thorax, near the germs of the wings ; in the saw-flies (Lyda), in all parts of the 

 thorax and abdomen ; in larval flies (Musca), in the end of the abdomen, just in 

 front of the large terminal stigmata. The place where the blood corpuscles are 

 formed is usually near, or in relation with, the fat-bodies. But while the fat- 



