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TEXT-BOOK OF ENTOMOLOGY 



of the body, principally on the threads of the adipose body. In 

 the Orthoptera the absorption is immediately effected by means of 



the cells of the membrane 

 which separates the peri- 

 cardium from the cavity of 

 the body underneath the 

 heart. The regions where 

 the hard bodies are ab- 

 sorbed in great number 

 coincide with the regions 

 of formation of tbe blood 

 corpuscles. In his re- 

 searches on the larvae of 

 Hyponomeuta and other 

 Lepidoptera, Schaffer de- 

 scribes these regions as 

 forming a sort of island. 



Fro. 3S4. Section of the heart (c) and pericardia! cells 

 ( po, pc) from the posterior part of the heart of a fly : /, /, 

 nests of leucocytes situated between the heart and pericar- 

 dial cells. From a microphotograph, after Kowalevsky. 



The nests where the blood 

 globules are formed are the most active centres of phagocytosis. 



Balbiani, and also Cue"not, have supposed that the formation of the blood 

 corpuscles takes place in the pericardial cells, but Kowalevsky insists that these 

 cells cannot form the leucocytes, which 

 "are probably formed in different 

 parts of the body, notably in the 

 special nests [Hcrde of Jager] situated 

 near the heart, but outside of the 

 pericardial cells." 



In Fig. 384, where the nests of 

 leucocytes (I) are shown, it is evident 

 that they are formed where observed, 

 and "could not have come from the 

 pericardial cells, which have their own 

 structure and their special function," 

 these cells being very large and char- 

 acteristic. 



In Kowalevsky 's preparations of 

 Truxulis, the pericardial cells with 

 deposits of carmine and the groups of 

 leucocytes (Fig. 385, I and I') stained 

 with India ink, we have to deal with 

 elements absolutely different. If the 

 formation of leucocytes was caused by 

 tin; pericardia! cells, these last would 



be obliged to free themselves from 

 their contents and to modify their 

 essential nature. 



Fio. 885. Cross-section of the heart of 

 7'rii.rnl!x IKI.SH/, i and of the structures around 

 it: c, heart; ?p, epithelium under the cuticula 

 (liypoderinisl ; ,n\ ovarian tubes; pc. pfri- 

 rardial cells, with urn- or two nuclei containing 

 a deposit of carmine; / ami /'.group of leucocytes, 

 which have absorbed granules of India ink. 

 After Kowalevsky. 



