Gilson's glands were first studied in detail in the larvae of Phryganea 

 grandis, Limnophilus rhombicus,L,flavicornis, L.extricatus 

 and Anabolia nervosa (Henseval, 1896:329— 355) and then in the larvae 

 of several other species (Vorhies, 1905:118; Branch, 1922:269-270; Brocher, 

 1923); they are simple or branched tubular glands. In species of Limno- 

 philinae, Gilson's glands are simple tubes situated in the middle of the 

 1st thoracic segment; it opens at the tip of the prosternal process ("horn") 

 of the larva (Figure 5l). In species of Phryganea, Gilson's glands are 

 bilobed and situated in each of the three thoracic segments, near the ventral 

 nerve chord (Figure 53). The glarids of the prothorax are larger than the 

 other two and their lobes form a network of tubes; the ducts of the lobes 

 join near the subesophageal ganglion, forming a small reservoir, the narrow 

 44 duct of which opens at the end of the prosternal horn. The lobes of the glands 

 of the meso- and metathorax consist of several branches; the excretory 

 ducts of these lobes join and open in one pore in the intersegmental fold of 

 the segment. The walls of the gland consist of one layer of large secretory 

 cells with a radially striated protoplasm and large nuclei (Figure 52). The 

 secretion of the gland is a transparent oily emulsion (Gilson, 1894; Henseval, 

 1896; Lubben, 1907:Figure 2; Vorhies, 1905:1 15-117; Branch, 1922:268-269; 

 Beams and Wu, 1929:261-278; Haller, 1948:320-328; Brickenstein, 1955:8-13). 

 The glands of caddis flies of the USSR were described by Zarechnaya (1963). 



(45) 



FIGURES 54-56. Ventral nervous system (after Branch): 



54 — Hydropsychodessp.; 55— Phryganea sp.; 56 - 

 Limnophilus sp. Figures 55 and 56 show the position of 

 the gonads. 



40 



