HERPETOMONAS ELMASSIANI. 331 



organism present had more than one stage in its life-history in 

 the insect, and to find exactly its relation to the salivary gland 

 tissues and secretion. 



The study of the morphology of the gland in which the flagel- 

 lates occurred required complete series of serial sections of three 

 insects. The gland of one of these was reconstructed section by 

 section, for the lobes of the gland cannot be readily visualized 

 'from the separate sections. Sometimes but one or two show, 

 at other times there appear to be five or six lobes because of the 

 inclination of the section and the twists in the organ itself. 



HISTOLOGY OF THE SALIVARY GLAND. 



The salivary gland nearly fills the dorsal half of the thorax. 

 Its efferent duct leads away from the point at which the three 

 lobes come together, first running back toward the abdomen 

 immediately under the gland, then turning and running forward. 

 It dips beneath the oesophagus near its junction with the pro- 

 ventriculus, and beneath the ventral chain of nerve ganglia 

 between the sub-cesophageal ganglion and the ganglion immedi- 

 ately posterior to it. From this point the duct runs forward to 

 the mouthparts where its secretion enters the pump or syringe 

 and the hypopharynx. 



It was interesting to note that the three parts of the gland 

 could be distinguished readily in iron haematoxylin eosin sections 

 by the character of the secretion in each, in spite of the fact that 

 the outline of each might be most deceptively placed according 

 to the plane of the section. The anterior lobe contained frothy 

 material staining pink with eosin. The ventral lobe was dis- 

 tended with a smooth or very slightly granular substance which 

 also stained pink with eosin. It was thus easy to distinguish 

 these two by the consistencies of their contents. The dorsal lobe 

 was remarkable in that its fluid retained some of the iron haema- 

 toxylin stain and in addition picked up eosin eagerly, nearly 

 attaining the brilliant orange red color characteristic of blood 

 corpuscles in tissues stained for example with Delafield's (not 

 Heidenhain's) hcematoxylin and eosin. 



