Pcim iiia C^dlcjic. Clarcinoiit, California 45 



In the past I have been inclined to consider these as in part at 

 least with conductive function, but I am sure the true nerve cells 

 are sometimes bipolar, possibly in some cases multipolar with 

 fibers running longitudinally and laterally in the nerve strands. 

 The true nervous elements are more delicate, their fibers or fibrils 

 cross each other at various angles but bear no other obvious 

 relations to each other. 



Among the earliest works on the nervous system and sense 

 organs of starfish is that of Hacckel in 1859. In 1860, Wilson has 

 a remarkably clear and accurate paper on the nervous system of 

 the starfish. Another early paper was by Owsiannikow in 1871. 

 Teuscher in 1856, figures the nervous system but not in much detail. 

 Ludwig, 1878, has his figure of the nervous system in section often 

 copied. Hamann, 1883-5, shows more of the structure of the 

 nervous system and gives a good idea of the structure of the eye. 

 Cuenot. 1887, gives a clearer idea of eye structure but not much 

 more about the detail of the nervous system. Jickeli, 1888, recog- 

 nizes four chief parts of the nervous system of starfish: (1) The 

 ambulacral, (2) the sub-epidermal body plexus, (3) the deep 

 nerves, (4) the intestinal nervous system. Pfeffer, 1901, studies 

 the eyes particularly and distinguishes clearly between support- 

 ing cells and nerve cells. More recent papers of Pietschmann, 

 1906, and especially of Meyer, 1906, show details in the nervous 

 system. The last author distinguishes clearly between supportive 

 cells and nerve cells in the nervous system. He finds the suportive 

 cells uni- or bipolar and usually running from the ventral to the 

 dorsal side of the nerve bands. The nerve cells are bipolar or 

 multipolar with fine branches. 



Romanes, 1885, found besides strong negative reactions against 

 injurious stimuli, positive reactions of a chemical nature which 

 he considered due to the sense of smell. This sense depended 

 somewhat on the physiological condition of the animal, chiefly 

 upon its degree of hunger. A starfish, kept several days without 

 food, immediately crawled near some presented. If a small bit of 

 food be withdrawn as the animal approaches, the starfifish could 

 be led about in any direction. By severing various parts of the 

 rays, Romanes found that this so-called olfactory sense was equally 

 distributed throughout the length of the body and by varnishing 

 the upper surface he found that the reactions were unaff'ected. 

 Also by placing a bit of food on the alioral surface no reaction 

 occurred. Preyer, 1886, found great difi'erences in individuals 

 when stimulated with food. 



Starfish are positively phototropic but largely lose this ten- 

 dency if the eye-spots are removed. Romanes found the sensi- 

 tiveness so great that starfish discriminated between ordinary pine 

 boards covering the tank and the same boards painted black. 

 Romanes Preyer, Jennings and others have studied the righting 



