ANTHOZOA HYDROIDA. 87 



Sir J. G. Dalyell, in his most valuable work on " the rare 

 and remarkable animals of Scotland/^ follows out at greater 

 length his observations recorded in the ' New Philosophical 

 Journal/ " Nothing/'' he observes, '' can be more remark- 

 able to the spectator than finding the progeny free while 

 the parent is immoveably fixed — sufficient evidence that 

 there is nothing of vegetable nature in such zoophytes. It 

 is as strictly an animal product as an Alcyonium or an Asci- 

 dia, whose oiigmdX corpiisculum,planula, spinula, larva (by 

 whatever name it may be called), which by nature becomes 

 riveted to some solid sustaining foundation. The nascent 

 Tubulana thus formed, and capable of selecting its position, 

 loses that faculty never to be regained, and is rooted at an 

 indefinite period — sometimes in the course of one day, some- 

 times on the lapse of two. But quiescence is essential here. 

 Should frequent disturbance alter its place, the adhesive 

 power seems to be impaired, or the creature rendered incapa- 

 ble of its exercise. The movement of those that are rooted in 

 early age is commonly much more rapid than that of others. 

 Specimens discharged from the cyst on the 1st of January, 

 and affixing speedily, were about four lines high in seven 

 days. Those whose adhesion had not ensued were infinitely 

 smaller. With the latter it is not improbable that, instead of 



