SECT. IX EXCRETORY AND OTHER GLANDS 127 



fissure on the Inner side of the under Hp, almost 

 within the mouth. Their whole structure indicates 

 that they are acicular glands. The ducts are long 

 chitinous tubes which lead to a chitin-lined sac with 

 a very fine epithelium, their proximal ends being 

 attached to the body wall by muscle bands just as 

 are the setiparous sacs in the Annelids. The figure 

 shows the course of these long glands. What the 

 exact function of the two glands, opening together in 

 the mouth, may be, it is impossible to say. In all 

 preparations they are found to be strongly contracted, 

 so that the chitin-lined lumen is to be seen only with 

 difficulty. 



These " salivary " glands, developed out of acicular 

 glands, are especially interesting as compared with the 

 salivary glands of Peripatus, which have been shown 

 to be transformed nephridia. In both cases the 

 openings of the glands have united in the middle line. 

 In both cases we have to assume that, the acicula or 

 the secretions of their glands on the one hand, the 

 excretion from the nephridia on the other, assisted the 

 jaws in their alimental functions as the first step 

 towards their differentiation into salivary glands. 



TJie Acicular gland of the aiitcnnal parapodia or 

 Antennal gland. — In Apus we could find no certain 

 trace of an antennal gland at the base of the second 

 antennae ; a slight indentation on the basal sw^elllng 

 seemed, however, to indicate that there had been 



by the early use of the acicula as teeth, which would make our choice 

 fall between i and 2, we think the last view is the most probable, 

 although we do not reject the second alternative. 



