I. TRÄGÅRDH, METAMORPHOSIS AND BIOLOGY OF ORCHESTES. 19 



a cocoon, the malphigian tubes act as spinning glands, it 

 seemed highly probable, that the same would be the case 

 with O. fagi and O. quercus. 



In order to asoertain, whether it was so or not, I dissected 

 a lar va O. fagi. 



Fig. 3, Pl. 1, represents the alimentary canal of this 

 larva. 



We notice, that the short oesophagus widens into a very 

 large chyle stomach, which is divided into two parts, one 

 oval, sack-shaped anterior part which is constricted posteriorly, 

 where it opens into a narrower posterior part, which makes a 

 coil to the left and then turns straight backwards and at 

 the same time becomes narrow and of even width; this part, 

 which has 12 — 14 short cseca, turns abruptly, runs forward 

 for about V2 oi its own length and turns once more abruptly 

 backwards and passes into the hind intestine. Exactly behind 

 the constriction which separates the chyle stomach from the 

 hind intestine the urinary tubes open. There are two pairs 

 of them; they are very well developed and run forward 

 beyond the middle of the anterior part of the chyle stomach, 

 where they turn abruptly backwards. 



The hind-intestine is narrow and straight in the proximal 

 Vä, makes about in the middle of its own length a coil to 

 the right and continues straight towards the anal opening 

 and widens slightly at the same time. 



As there are no other glands, it is obvious, that also in 

 O. fagi and O. quercus it is the malphigian tubes which serve 

 as spinning glands. 



It it also evident that the conical shape of the lOth 

 segment is an adaption for the purpose of spinning. In O. 

 popidi, who does nat make any cocoon, the pygidium is not 

 conical and pointed. 



The walls of the cocoon are comparatively firm and the 

 tissue resembles very much that of the cocoon of Lebia 

 [comp. Fig. 9, Pl. I, and Silvestri Fig. 7, Pl. IV]. 



The threads are fine and run across one another in 3 — 4 

 thin layers, and in many places 2 — 3 have coalesced. 



The larva of Lebia is consequently not the only one, 

 which rejoices in the ability to use the urinary tubes as 

 sericiparous glands, but also the larvse of Orchestes s. str have 

 this faculty. 



