THE PARABLAST1C TISSUES. 273 



Phagocytes. It has long been known that amoeboid blood 

 cells are capable of enclosing molecular material, bacteria, etc., 

 in their protoplasm, in point of fact, of feeding like amoebae. 

 During the histolysis of the larval tissues, the number of 

 white blood cells rapidly increases, and many are seen with 

 several nuclei. They are found surrounding, penetrating, or 

 imbedded in the larval tissue in process of degeneration. 

 These cells ultimately become loaded with globules of oil, and 

 even with solid fragments of muscle. In this condition they 

 were termed by Weismann [2] granule cells (Kurnchenkugeln). 

 He further distinguished large and small granule cells. The 

 large ones Viallanes terms ' corps rosea.' They appear to be 

 merely overgrown and loaded leucocytes (PI. XVI. , Fig. 4, 

 and PI. XVIII. , Fig. 6). These are very numerous in the 

 blood of the nymph, and some still remain in that of the 

 young imago. The large granule cells are generally seen 

 to be surrounded by young leucocytes, which appear to be 

 feeding upon them, and some may be actually observed pene- 

 trating them by means of pseudopodia. It is clear to me that 

 there is a continual transference of granules from cell to cell, 

 those which are overloaded being attacked by younger and 

 more vigorous leucocytes, which become granule cells, and are 

 in turn themselves attacked by a succeeding generation of 

 phagocytes, until the whole of the effete tissues of the larva 

 are assimilated (see ' Histolysis of the Larval Tissues,' 

 Chap. IX.). 



The Connective Reticulum resembles the adenoid or retiform 

 tissue of Vertebrates, and consists of a network of stellate 

 branching cells and endothelial plates. It permeates the whole 

 body cavity, and forms the subhypodermic cellular layer and 

 the so-called peritoneal coat of the tracheae and viscera. The 

 smaller tracheal capillaries are excavated in the stellate cells of 

 this reticulum.* 



* The intracellular origin of the tracheal capillaries has been observed in the 

 larvae of Lepidoptera and Ichneumonidte by Hermann Meyer, Zeitsch. f.w. Zool., 

 Bd. i. In Dipterous larva; by Weismann [2]. In Lampyris by Wielowiejski 

 [138]. In the fat bodies of Luciola italica by Emery [139]. Under the 



