51 



it expelis the liquid formed in the 

 glaiids. 



In the following description I shall 

 deal first with one half of the appara- 

 tus, that is the glands and ducts on the 

 right side of the digestive tube, and 

 afterwards with the impair organ (sali- 

 vary pump) which expelis the saliva. 



Accessory gland. 



The posterior gland is rounded, has 

 very thin and transparent walls and is 

 closely connected with the walls of the 

 proventriculus by branches of the tra- 

 cheas. 



It is easily distinguished from the 

 surrounding tissues, if the head of the 

 specimen be severed on the day prece- 

 ding examination, as the citrine liquid 

 which accumulates within, distends its 

 walls and makes it more conspicuous. 



In adult specimens of Triatoma me- 

 gista it has the following dimensions. 



ÍLenglh: 1,35 mm. 

 "^ I Width: 1,2 mm. 



ÍLenglh: 1.4 mm. 

 Width: 1,3 mm. 



As for its structure, it is composed of 

 a delicate basal membrane and a layer 

 of flattened pavement cells. It is consi- 

 dered a mere deposit or receptacle of 

 .saliva, as expressed in the denomination 

 Accessory salivary gland. 



At the anterior and external pole 

 of this gland begins an excretory tube, 

 which is the accessory duct; it runs pa- 

 rallel with the oesophagus, penetrates 

 into the cephalic cavity, describes a loop 

 after which it runs in the opposite di- 

 rection and finally opens into the mid- 

 dle or supplementary gland. The mea- 

 surements of the accessory duct are as 

 following : 



j jtotal: 6,0 mm. 



j Length jto the: loop 3,5 mm. 



Irefiected part: 2,5 mm. 



I greatest: 0,1 mm. 

 ^'^'***^ Ismallcst: 0,045 mm. 



9 I 



Lenath 



Width 



toial; 7,5 ram. 

 to the loop: 4.Ü ram. 

 reflected part: 3,5 mm. 

 greatest: 0,12 mm. 

 smallest: 0,050 mm. 



Supplementary gland. 



The supplementary gland is a little 

 above the former one, at the side ot the 

 initial portion of the proventriculus. 

 The connection between it and the prin- 

 cipal gland is so close that some authors 

 consider it a diverticle of the same. 



It is pear-shaped and has the follo- 

 wing dimensions: 



(Length: 1,2 mm. 

 ^ \Widlh: 0,62 mm. 



jLength: 1,12 mm. 

 ^ t Width: 0,64 mm. 



The structure in the same as that 

 of the accessory gland, that is a single 

 layer of cells on a basal meml)rane. This 

 histological identity leads rae to consider 

 it also merely as a receptacle of saliva. 



The other end of the accessory duct 

 opens in its middle part. 



Principal gfand. 



The principal gland is directly con- 

 nected with the supplementary gland 

 and occupies a place in front and out- 

 wards of the same. It is easily distin- 

 guished from the others, which arc light 

 and transparent, by its remarkable opa- 

 city and dirty yellow color. 



It is kidney-shaped and has the fol- 

 lowing proportions : 



íLenglh: 1,25 mm. 

 ■^ IWidth: 1,0 mm. 



ÍLenglh: 1,37 ram. 

 "^ I Width: 1,08 mm. 



The histological structure of this 

 gland is very different from that of the 

 former, as it is typically glandular with 

 high, polycdric glandular cells, often 



