334 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Even though one may be fortunate enough 

 occasionally to get a good idea of the shape of the brain, 

 it is better to complete the investigation by means of 

 serial sections, which are, of course, necessary for a 

 proper examination of histological details, both in the 

 brain and ventral nerve cord. Many attempts were made 

 to make use of intra-vitam methods of staining, as it was 

 hoped that the nervous system would be rendered more 

 distinct when the tissues were stained in the living 

 condition. These attempts, however, were not successful, 

 as the stain (methylene blue) penetrated the body wall 

 very slowly and incompletely, and did not reach the 

 nervous system at all. 



The Cerebral Ganglia, as in most aquatic Oligo- 

 chaeta, lie far forwards, just behind the prostomium. 

 Their posterior border lies at the level of the boundary 

 between the buccal cavity and pharynx. They are dorsal 

 in position, and form a comparatively large brain, the 

 structure of which is complicated by the presence of 

 several lobes. The brain is concave behind and in front, 

 and consists of a solid mass of nerve fibres and nerve cells. 

 Anteriorly it is produced into three horns or lobes, two 

 lateral and one median : the former may be described as 

 the antero-lateral lobes, and the latter as the anterior 

 median lobe (PI. I, fig. 1, an.l. ;m.l.). From these, nerves 

 arise which will be considered later. The anterior 

 median lobe is characteristic of the family Tubificidse, 

 but is not always present as a simple lobe. In a few 

 more highly specialised forms, e.g., Bothrioneuron, it 

 consists of a median nerve communicating with a small 

 ganglion placed a little way in front of the brain 

 (Beddard). 



The antero-lateral lobes described above are not 

 figured by Vejdovsky (1884) in his drawing of the brain 



