ORGANS OF SECRETION. 58l 



gastric sac, or straight alimentary tube. The salivary glands 

 consist of one or more simple undivided tubuli opening into 

 the mouth, and even the testis and ovary have still the 

 simplest glandular form of elongated tubuli. 



The liver is not less obvious in the rotiferous animalcules, 

 where it consists of isolated tubuli, varying much in their 

 number and size, and opening directly into the wide gastric 

 cavity. Two of these hepatic tubuli are seen in brachionus 

 urseolaris, four in megalotrocha alba, seven in diglena lacus- 

 trisy nine in enteroplea hydatina, some dozens surround the 

 stomach in rotifer vulgaris, and in philodina roseola the 

 entire length of the digestive cavity is closely enveloped 

 with simple, short, straight, parallel biliary follicles, as in 

 many of the higher annelides. These various tubuli are 

 commonly dilated at their closed ends, as in most other 

 glands ; and the difference of form and place of insertion of 

 these tubuli, would induce a belief of their having sometimes 

 different functions, and representing both liver and pancreas, 

 as in the enteroplea hydatina, where seven long narrow 

 biliary tubuli open into the upper cardiac portion of the 

 stomach, and at some distance below two very different short 

 wide follicles, like the rudiment of a distinct pancreatic 

 gland. The salivary glands are generally represented in the 

 rotifera by two simple dilated follicles connected with the 

 sides of the masticating apparatus. The male and female 

 genital organs have also here a simple tubular structure, the 

 internal branchiae are in form of ramose tufts, the vesicula 

 seminalis is a single median follicle, and a few of the species 

 secjete upon their surface extravascular silicious laminae, 

 forming an enveloping sheath, like the polygastrica. 



The high development of the chylopoietic glands of the 

 cirrhopods, and the form and connexions of these organs, 

 constitute further affinities between them and the mollus- 

 cous classes, and accord with their imperfect means of select- 

 ing and obtaining the more nutritious kinds of aliment. 

 The liver is of great size, and consists of innumerable small 

 biliary follicles or cryptae, arranged in clusters or acini, which 

 form several lobes on each side of the stomach. These 

 lobes surrounding the stomach open into different parts of 

 its cavity by short wide biliary ducts, as in most mollusca. 

 Two large conglomerate salivary glands pour their secretion 



