A Reconstruction of the Nervous System 

 of a Nemertian Worm 



WILLIAM A. IIILLON 



Small specimens of Cariiiclla chiyiilcila Cole were fixed in Mer- 

 curic chloride and cut in series. A general hematoxylin stain was 

 very satisfactory for general anatomy. I'Or a study of the liner 

 structure other preparations will he necessary. 



No attempt will he made to gi\e a complete review of the litera- 

 ture relating to this group. Almost e\ery systematic paper has 

 something, because of the importance of the nervous system in classi- 

 fication and because in many cases the nersous system may be seen 

 through the body-wall without dissection. 



One of the first extensi\e accounts of these animals which also 

 included quite a consideration of the nervous system was Mcintosh 

 in 1874. Several of the genus Nemestes were studied and the gen- 

 eral form of the nervous system shown. Amphipheris is shown in a 

 similar manner with a single lobe of the brain and with the two 

 brain commissures. Tetrastemma is shown in a similar manner. 

 Hubrecht in 1887 has an extensive paper in which the details of 

 several nervous systems are shown as they show in reconstructions 

 from sections. F'upolia girardi is especially well shown with its 

 small dorsal and large \entral commissure and with three brain 

 lobes. It is in this paper that Hubrecht makes his interesting com- 

 parison between the nemertians and cordates. In his paper of 1880 

 he has shown the structure and position of different parts of the 

 nervous system of nemertians, especially of Cerebratulus of which 

 he gives a very good figure. In this he shows a reconstruction of 

 the brain with its chief ner\'es, ventral and dorsal commissures, 

 general position of the cells, the two lobes of the brain on each 

 side and the chief ner\ es. He also treats of nemertian nervous 

 systems of many other forms, but not in st) much detail. 



Burger in 1890, '91, has extensive papers on the nervous 

 system of the group. He discusses not only the general form, but 

 also the minute structure of the nervous system of a number of dif- 

 ferent types. In 1895 Burger has another important paper on this 



