156 Sir John Graham Daly ell on a Singular Mode of 



I found several spinulae swimming there in twenty-four hours. 

 Nothing else could be found. 



However a number of oval yellow or reddish corpuscules 

 next appearing at the bottom of the smaller vessels, they proved 

 so many ova under the microscope, each containing a visible 

 embryo spinula. 



Some had nearly attained maturity ; the head or body formed 

 the centre encircled by the tail as a circumferential border ; all 

 contained within an exceedingly transparent integument or am- 

 nios. All the ova were motionless. 



This was an important observation, for it leads to the solu- 

 tion of certain difficulties perplexing even very learned natura- 

 lists, who have been inclined to deny the animal nature of those 

 beings in activity which are indisputably an earlier stage of 

 zoophytes becoming permanently rooted in a later stage. 



I now beheld an inert ovum — necessarily inert, because this 

 constitutes one of the principal elements in the definition of an 

 ovum ; it is a stage of organic existence, void of locomotion. 

 But, subsequent to impregnation or when the organic matter of 

 the ovum is advancing to another stage, the embryo is at first 

 in a passive, and then in an active organic state, which may exhibit 

 the locomotive faculty before production, as seen in some planariae, 

 traversing the capsule enclosing them, and in other animals. 



Those observers, therefore, who witness the activity of the 

 corpuscles from the flustrae, or of the planulae from the sertula- 

 rias, or of the spinulae from the ascidia, suppose it only the 

 first, while truly seeing them in the second stage. They have 

 quitted the ovum. 



The evolution of the spinula in the present subject, follows 

 production of the ovum so speedily as accounts for the diffi- 

 culty of finding it in this earlier stage. 



The spinulas having escaped their prison, they traverse the 

 water with considerable activity, in all different directions, and 

 assuming all different positions ; their motions and their figure 

 bearing a near resemblance to those of tadpoles. Sometimes the 

 spinulae of the preceding paragraph continue ten or twelve days 

 in motion. Here it relaxes sooner; their transition is less fre- 

 quent and more circumscribed ; they are seen with the head 

 down and the tail erect as the others, almost stationary, but 



