64 THE WHENCE AND THE WHITHER OF BIAN 



far more controlling, perceptive, ganglionic material 

 than in lower worms. Furthermore the supra-ceso- 

 phageal ganglion is relieved of a large part of the di- 

 rect control of the muscles of each segment, and is 

 becoming more a centre of control and perception for 

 the body as a whole. It is more like our brain, com- 

 mander-in-chief, the other ganglia constituting its staff. 

 The sense-organs have improved greatly. There are 

 tentacles and otolith vesicles as very delicate organs 

 of feeling, or possibly of hearing also. 



But the annelids were probably the first animals to 

 develop an eye capable of forming an image of ex- 

 ternal objects. The importance of this organ in the 

 pursuit of food or the escape from enemies can scarcely 

 be over-estimated. The lining of the mouth and phar- 

 ynx can be protruded as a proboscis, and drawn back by 

 powerful muscles, and is armed with two or more homy 

 claws. Eyes and claws gave them a great advantage 

 over their not quite blind but really visionless and 

 comparatively defenceless neighbors, and they must 

 have wrought terrible extinction of lower and older 

 forms. But while we cannot over-estimate the im- 

 portance of these eyes, we can easily exaggerate their 

 perfectness. They were of short range, fitted for see- 

 ing objects only a few inches distant, and the image 

 was very imperfect in detail. But the plan or funda- 

 mental scheme of these eyes is correct and capable of 

 indefinitely greater development than the organs of 

 touch or smell, perhaps greater even than the otolith 

 vesicle. 



And the reflex influence of the eye on the brain was 

 the greatest advantage of all. Hitherto with feeble 

 muscles and sense-organs it has hardly paid the animal 



