40 Thomas Menry Huxley 



the anatomy in contrast to the individual peculiarities. 

 He shewed that microscopically all the complicated 

 systems of canals and organs were composed of two 

 " foundation-membranes," two thin webs of cells, one 

 of which formed the outermost layer of the body, while 

 the inner formed the lining of the stomach and canals 

 in the thinner parts of the body, such as the edges of 

 the umbrella-like disc, and towards the ends of the 

 tentacles. These thin webs formed practically all the 

 body. In the thicker parts there was interposed be- 

 tween them an almost structureless laj^er of jelly, placed 

 like padding between the lining and the cloth of a coat. 

 He shewed that blood-vessels and blood were absent, 

 in which he has been confirmed by all other observers. 

 He declared more doubtfully against the existence of a 

 special nervous system, and it was not until long after, 

 when the methods of microscopic investigation were 

 much more perfect, that the delicate nerve-cells and 

 nerve-fibres, which we now know to exist, were dis- 

 covered. 



Having thus shewn the peculiar organisation of the 

 group he turned to seek out its allies among other 

 families. The Medusae consisted essentially of two 

 membranes inclosing a variously shaped cavity inas- 

 much as all its organs were so composed. The gener- 

 ative organs were external, being variously developed 

 processes of the two membranes. The peculiar organs 

 called thread-cells — poisoned darts by the discharge of 

 which prey could be paralysed — were universally pre- 

 sent. What other families presented these peculiarities ? 



There are to be found abundantly in sea-water, and 

 less frequently in fresh water, innumerable forms of 

 animal life called Zoophytes or animal plants because 

 they occur as encrusting masses like lichens, or 



