26 WILLIAM PATTEN. 



which extend outwards over the surface of the buds into the 

 large pore canals (fig. 9, n. c). 



There are some remarkable organs scattered about in the 

 subdermal tissue of the olfactory region of the adult(fig. 21,^.). 

 They are irregular, usually oblong, spindle-shaped, or branched 

 masses of small cells, whose nuclei stain deeply. They are 

 consequently very conspicuous, and I at first took them for 

 ganglia connected with the nerve-plexus ; but I have found 

 them in other parts of the body where there seemed to be no 

 plexus, so their nature is doubtful. When examined under a 

 high power the nuclei appear to be surrounded by concentric 

 layers of protoplasm, giving the whole mass a very character- 

 istic appearance. In some places the cells are so loosely 

 packed that they fail to touch one another ; they then lose 

 their concentric striations, and appear like masses of blood- 

 corpuscles. Usually a blood-vessel passes through the centre 

 or along the side of the bodies in question. In cross sections 

 the central blood-channel is seen to be either empty, filled 

 with a dark coagulum, or crammed with blood-corpuscles, 

 which in some cases are difficult to distinguish from the cells 

 composing the surrounding tissue. The nuclei of the cells 

 usually arrange themselves concentrically about the blood- 

 vessel. In other cases these problematical organs contain 

 a central canal, or irregular space, through which passes one 

 or more nerve-strands. The nerve-strands may run over or 

 through these organs, dividing into several branches on the 

 way, but emerging at the opposite end without any apparent 

 diminution in size, and without any intimate connection with 

 the organ. 



B. Physiology of the Olfactory Organ. — The anato- 

 mical features of the olfactory organs are sufficiently remark- 

 able to make any physiological experiments as to their function 

 of great interest and importance. Their similarity to the 

 gustatory organs on the inner mandibles might lead one to 

 expect that stimulating them with food would produce reflex 

 chewing movements. But although I have made repeated 



