THE ACTIVITIES OF CORYMORPHA 329 



muscle of the stalk, are completely under nervous domination. 

 Some of these, such as the longitudinal muscle of the proboscis, 

 exhibit responses which are called forth in such a way that they 

 are indistinguishable from a reflex in the higher animals. From 

 this standpoint Corymorpha reproduces in miniature all the 

 conditions found in anthozoans. And this is further emphasized 

 by the lack of any general nervous center and the consequent 

 great independence of all organs from the side of their neuro- 

 muscular activity. Corymorpha, therefore, does not seem to fill 

 the gap between the extremely simple effector system of sponges 

 and the receptor-effector systems of anthozoans, but rather pre- 

 sents a reduced though not simplified state of the anthozoan 

 type. If the muscles of Corymorpha were more commonly open 

 to direct stimulation than they are and if its activities presented 

 less that can be interpreted in the nature of a reflex, it might 

 supply more nearly the requisites of an intermediate type, but 

 as it is it resembles rather a reduced anthozoan than a form in 

 any sense intermediate between sponges and sea-anemones. 



9. SUMMARY 



1. Of the four classes of effectors commonly found in coelen- 

 terates, mucous glands, cilia, nettle cells, and muscles, Cory- 

 morpha possesses only the last two. The nettle cells are not 

 under the control of the nervous system; the muscles may or 

 may not be so controlled. 



2. Corymorpha has four ectodermic muscles: the longitudinal 

 muscle of the stalk, the longitudinal muscle of the proboscis, 

 and the longitudinal muscles of the proximal and of the distal 

 tentacles. These four muscles are under the control of the 

 nervous system. It has two entodermic muscles: the circular 

 muscle of the stalk and the circular muscle of the proboscis. 

 Both are stimulated directly, but the second is probably also 

 under partial nervous control, 



3. Nervous transmission in Corymorpha is diffuse except 

 in the stalk, where it is predominantly longitudinal. 



