62 COELENTERATA 



a colony in caustic potash. What purpose do such spicules 

 serve? 



Parker: The Reactions of Metridium to Food and Other Substances. 



Bull. Mus. Comp. Zool.,- Harvard, 29, 1896. 

 : The Mesenteries and Siphonoglyphes in Metridium marginatum. 



Bull. Mus. Comp. Zool., Harvard, 30, 1897. 

 : Longitudinal Fission in Metridium marginatum. Bull. Mus. 



Comp. Zool., Harvard, 35, 1899. 



The Reversal of the Effective Stroke of the Labial Cilia of Sea- 



Anemones by Organic Substances. Am. Jour. Physiol., 14, 1905. 



The Origin and Significance of the Primitive Nervous System. 



Bull. Mus. Comp. Zool., Harvard, 50, 1911. 

 — : The Elementary Nervous System. Lippincott, 1918. 



