NO. 10 FEEDINC; ORGANS OK AKAC II N IDA -SNODCRASS I9 



played in digestion by the secretion of the secretory cells. Oetcke 

 (1912) believed that the tissues of the prey are first dissolved by 

 secretion of the salivary glands, and that the liquefied food is then 

 taken into the digestive cells, where it is digested by the digestive 

 secretion absorl)cd from the secretory cells. According to Kocslcr 

 ( 1934), Schlottke ( 1934), I'" rank ( 1938), and P.ader ( 1938), however, 

 a preliminary digestion by enzymes from the .secretory cells takes 

 place in the lumina of the diverticula, after which the process is com- 

 pleted within the digestive cells (presumably by enzymes formed in 

 the latter). It thus ajipears that only the final i)hase of digestion is 

 intracellular. 



The digestive i)rocesses of Li)iuiliis. as described by Schlottke 

 (1935), are similar to those of the .\rachnida. After the food has 

 been ground up in the proventricular gizzard it is passed into the 

 central lumen of the stomach, where it is deluged with digestive fluid 

 from the many-branched diverticula, containing protease, carlxDxy- 

 polypeptidase, amylase, and lipase. In a state of "prcdigestion" the 

 liquefied food is then forced into the end branches of the diverticula 

 and absorbed by the digestive cells, within which a dipeptidase com- 

 pletes the process of digestion. Similarly in the I'ycnogonida Schlottke 

 (1933a) has shown that digestion takes place intraccllularly in the 

 absorptive cells of the stomach diverticula. The ingested food of the 

 pycnogonids. however, Schlottke says, contains no particles and no 

 recognizable fragments of the tissues of the prey, a fact suggesting 

 that the secretion cells of the stomach, which become active before 

 feeding, must play some part in the liquefaction of the food, since the 

 filtering apparatus of the stomodaeum could hardly be supposed to 

 reduce the food to a liquid condition by mechanical action. 



Some arachnids, particularly the Araneida, are well known to 

 practice extraoral digestion. The solvent fluid discharged from the 

 mouth has been generally supposed to be a product of the salivary 

 glands, but the amount of the liquid exuded from the mouth is 

 often so great that it would seem more probable, as contended by 

 Kastner (see Gerhardt and Kastner, 1937), that it comes from the 

 stomach diverticula. 



II. THE PALPIGRADI, OR MICROTHELYPHONID.\ 



The members of this order, comprising about 20 known sjxcies. 

 are minute creatures, mostly tropical or subtropical in distribution, 

 with species in the Mediterranean region of Kuroj^c, and in Texas 

 and California of the United Stales. The podipalps of these arachnids 



