80 Descriptions of Preparations. 



the larva. The stomach succeeds to the oesophagus, from which it 

 is readily distinguished by the opacity of its walls and the tracheae 

 which are distributed to it in great abundance. Bands of oblique 

 muscles are observable decussating superficially^ and longitudinal 

 muscles lying at a deeper level in its walls. The tubular renal 

 organs, the so-called ' Malpighian vessels/ are seen upon the pos- 

 terior half of the stomach, forming two loops on either side, the 

 mesially placed being shorter than the more externally placed 

 loops, and having its limb which passes towards the anal end of 

 the body bifurcated, whilst the returning limb of each outer loop 

 remains undivided. The two loops on each side thus form three 

 trunks which form an intricate interlacement in the posterior part 

 of the body-eavity, on either side of the intestine. The two stems 

 themselves fuse on either side into a single trunk, which opens 

 into the intestine a short way below the pylorus ; and as the 

 product of these tubules is uric acid, the portion of intestine below 

 their opening may be regarded as excretory, and that intercepted 

 between their opening and the pylorus, as corresponding func- 

 tionally with the small intestine. The point however at which 

 these vessels open into the digestive tract may vary, in difierent 

 orders, from the immediate vicinity of the pylorus to the immediate 

 vicinity of the anus. The looped portions of these organs are of 

 larger calibre than the more complexly convoluted posterior por- 

 tions ; from which they differ also in being smooth exteriorly, and 

 cylindriform, instead of having a moniliform appearance, from being 

 beaded over with sacculi. The rectum, which is considerably longer 

 than the small intestine, has its external surface divided into six 

 longitudinal strips by as many muscular bands; and the spaces 

 thus marked out are again subdivided by a very much larger 

 number of very much smaller transversely running muscular bars. 

 The long convoluted white tubes, the coils of which are seen to 

 commence with a blind end on either side, about opposite the 

 junction of the stomach and intestine, are the silk glands, and they 

 pass to the under surface of the digestive tract, anteriorly, to end 

 in a common duct opening in the modified labium or ' spinneret.' 

 Underneath the coils of the silk gland of the left side, a large trans- 

 parent walled bladder is seen, from the posterior end of which a 

 tubular gland passes off* to form the mass of convolutions called the 

 ' queue du vaisseau dissolvant ' by Lyonet in his elaborate mona- 



