34 WILLIAM PATTEN. 



demonstrated the existeuce of special gustatory organs on the 

 under side of the inner mandibles (4^ p. 11). On examining 

 this place (fig. 3, g. b.) one can readily detect just beneath the 

 smooth cuticle a yellowish granular mass, 7 or 8 mm. long and 

 3 or 3 mm. deep. Sections show that the cuticle is perforated 

 with an immense number of canals, something like those in 

 the olfactory region. The canals contain chitinous tubules 

 extending into the yellowish mass, which consists of innu- 

 merable gustatory buds, apparently exactly like those in the 

 olfactory organ, only much more numerous, and densely 

 packed together many rows deep. The chitinous tubules are 

 coarser than in the olfactory organ, and many of them are 

 thrown into complicated folds, as in fig. 16, b. I have wiped 

 off the surface over these organs very carefully, and stimulated 

 the organs and their nerves with electricity, but have never 

 seen a trace of any secretion appear there. 



When treated with chromo-acetic osmic acid, and stained in 

 hsematoxylin, most of the organs are darkened around the 

 base of the chitinous tubule, assuming the colour and appear- 

 ance of sensory tissues when treated with this reagent, while 

 the periphery stains a bright blue. It is possible that the 

 peripheral gland-like cells secrete a substance having special 

 powers to absorb certain chemical substances in the surrounding 

 media, and in this way the stimulation of the centrally placed 

 ganglion-cell is increased. But how the stimulus can reach 

 the organ through these long tubules^ which in some cases are 

 much coiledj is not easily understood. Some of the older 

 and larger organs seem to be quite empty and dead; others 

 stain a dense blue-black in hsematoxylin; while still others, 

 apparently young ones, show very little of this blue colour, 

 but stain dark brown in osmic acid, like ordinary sense organs. 



The same kind of buds, but isolated, are found thinly 

 scattered over the surface of the outer jaws, between the bases 

 of the spines. It is probably these organs which, after the 

 spines and the inner jaws have been removed, produce the 

 faint reflex chewing movements referred to in our description 

 of the physiological experiments (c?, p. 12). 



