20 WILLIAM PATTEN. 



cuticula has been peeled off, so that below where the tooth-like 

 spines should be there are large pores with projecting crater- 

 like summits {s. sj).), containing many pigmented cells. 



The olfactory buds vary a good deal in size and form. 

 They are usually spherical or pear-shaped, and composed of a 

 varying number of large pyramidal cells, the apices of which 

 sometimes surround a perfectly clear spherical lumen. The 

 appearance of the buds varies greatly according to the method 

 of preparation_, and other causes not clearly understood. In 

 some they appear perfectly empty, so that the organs look 

 like so many blank spaces in the tissue, with only a few cell 

 outlines visible ; or, in organs isolated by maceration in Bela 

 Haller^s fluid, a few cells may contain a very delicate spongy 

 reticulum (fig. 9), while others in the same organ may be 

 densely crowded with refractive globules, so that they resemble 

 certain gland-like cells that I have fouud associated with 

 sensory cells on the tentacles and mantle edge of Molluscs, 

 such as Area, Pecten, and Lima (' Eyes of Molluscs and 

 Arthropods,' p. 722). A dark multipolar cell with a large 

 nucleus can usually be seen in the interior of the organ ; it 

 looks like a ganglion-cell with two or more fibrous ends, the 

 course of which cannot be followed very far in sections. It is 

 undoubtedly the same dark ganglion-like cell so conspicuous 

 in the young stages of these organs (fig. 23). 



The clear lumen seen in the younger specimens, the chitin- 

 ous, duct-like tubule, and the whole appearance of these 

 remarkable structures point toward their glandular nature. 

 On the other hand, their extraordinarily rich nerve-supply, 

 and the unquestionable derivation of the whole group of organs 

 from a primitive segmental sense organ, seem to show equally 

 clearly that they are sense buds. 



Not till I was able to demonstrate experimentally that 

 similar organs in the inner mandibles were gustatory organs 

 did I feel satisfied that the '^olfactory buds'' were of a sensory 

 nature. I then studied them anew by macerating fresh mate- 

 rial, paying special attention to the central ganglion-cell and 

 its relation to the chitinous tubule. I did not succeed in 



