No. 2.] EPITHELIUM OF DRAGONFLY NYMPHS. 109 



the appearance of the food. Here it reaches its height in 

 something less than two hours, and in three hours is about 

 finished. It progresses slowly through the length of the ventric- 

 ulus, beginning at the posterior end in something less than 

 three hours, and being completed in six to eight hours after 

 feeding. Thus in the posterior end, where the cells are some- 

 what longer and more numerous, it will be seen the discharge 

 occupies a longer time. 



III. THE REPLACEMENT OF THE DISCHARGED CELLS. 



The long cells which extend from the basement membrane to 

 the lumen of the ventriculus and the little round cells nestled 

 together against the basement membrane form two markedly 



FIG. 7. A normal discharge of the digestive secretion from the same series as F ig. 6, x 105. 



different parts of the epithelium. The latter have been dis- 

 cussed under various names corresponding to the diverse views 

 held as to their function. They have been called cryptcs, driisen- 

 crypten, and driiscn by Basch, 4 Frenzel, 5 and Faussek 6 respec- 

 tively. More recently Visart 7 has considered them to be glands. 

 This view has been copied widely. 



They have been called germinal buds by Miall and Denny, 8 



4 BASCH, 1858: Untersuchungen iiber Chylopoetische und uropoetische System 

 der Blatta orientalis, Sitzungsbr. der k. k. Akad. Wiss. IVten, math.-nat. Klassc, 

 xxxiii. 



5 FRENZEL, 1885 : Einiges iiber den Mitteldarm der Insekten sowie iiber Epi- 

 thelregeneration, Archiv. Micr. Anat., xxvi. 



6 FAUSSEK, 1887: Beitrage zur Histologie des Darmkanals der Tnsekten, Zeit. 

 Wiss. ZooL, xlv. 



7 VISART, 1894: Contr. &c. tubo digerenti Arthropoda, Atti d. Soc. Toscano de 

 Set. Nat., xiii. Of this paper I have seen only abstracts. 



8 MIALL and DENNY: The Cockroach, London, 1886. 



