DIGESTIVE TISSUES 303 



outer epithelia. This almost always occurs in the villi of the mammal 

 intestine. It may be avoided by several devices, as the injection of the 

 fixative through the blood channels after the use of amyl nitrite. 

 Also by the complete killing of the tissue by the use of chloroform. 



The tissues are sometimes very delicate and susceptible to handling. 

 These fragile parts may often be fixed in situ, especially by the use of 

 fixatives containing formalin. Chrom-aceto-formol is one of the best 

 for this purpose. Gentle injections into the lumen and into the sur- 

 rounding cavities should be made. 



LITERATURE 



Cotte, Jules. "Contribution a 1'etude de la nutrition chez les Spongiaires," Butt.Scien. 



France Belgique, 7, 38, pp. 420-573. 

 Jordan, H. "Die physiologische-morphologie der Verdauungsorgane bei Aphrodite 



oculeata," Zeits f. Wiss. ZooL, Band LXXVIII. 

 Bizzozero, G. "Uber die schlauchformigen Driisen des Magendarmkanal und die 



Beziehungen ihres Epith. zu den oberflachen Epith. der Schleimhaut," Arch. f. mik. 



Anat., Band XLII, 1893, S. 82. 



Oppel, A. " Lehrbuch der vergleichenden mikroscopischen Anatomic," Jena, 1900. 

 Metschnikoff, E. " Untersuchungen iiber die intercellulare Verdauung bei wirbellosen 



Tieren," Arbeiten a. d. Zool. Inst. zu Wien, Band V. 

 Setowski, L. "Digestion in Wool-Eating Caterpillars," Butt. int. Ac. Sc., Crocovie, 1905, 



P- 535- 



