the Ova of Zoophytes. 153' 



has given enlarged representations of the forms which tlie ova 

 assumed while swimming to and fro, and of their appearance 

 when laid open. He observed, that the ova were all somewhat 

 egg-shaped ; that they passed through the oviduct with their ta- 

 pering end pointed forward ; and that, as soon as discharged, 

 they turned up their rounded thick extremity, and continued to 

 swim about with that extremity always forward (Cavolini, 

 Abhand. uber Pflanzen-thiere, p, 48). On cutting off a small 

 portion of the outer covering from the base of a polypus, he 

 generally observed five ova of a flesh-red colour, like those he 

 saw passing out through the oviducts. In the month of June, 

 he observed the polypi of the Gorgonia in the act of discharging 

 their ova ; a portion of this zoophyte, only six inches high, dis- 

 charged ninety ova in the space of an hour. The ova first 

 mounted in a spiral direction to the surface of the water, then 

 swam in a horizontal direction to the margin, without changing 

 their forms. Under the microscope, he repeatedly observed the 

 ovum change its lengthened form to that of a sphere, and when 

 the microscope was perfectly steady, he was surprised to see the 

 ovum bound off with rapidity from the place where it lay, and 

 keep itself in a constant quick motion as long as he watched 

 it (Abh. p. 48). " On looking again at the vessel in which 

 the Gorgonia lay (he says) I found that all the ova had ar- 

 ranged themselves round the margin, with their rounded thick 

 ends applied to the sides of the vessel, like a swarm of wood-Hce 

 on a branch ; and when I pushed them off with a needle, they 

 changed their forms in an extraordinary manner, while they con- 

 tinued to swim about in all directions." 



In the CaryophylUa calycularis Lam. (Madrepora calycula- 

 riB Lin.), Cavolini observed that the ova were, like those of the 

 Gorgonia, in a state of maturity in spring, and were discharged, 

 in the same manner, through small distinct openings between 

 each of the ten taenia. They were seen through the transparent 

 sides of the polypi to occupy a similar situation at their base ; 

 they had the same ovoidal shape, but were of a darker red co- 

 lour than those of the gorgonia, and somewhat larger. They 

 exhibited the same singular phenomena ; they glided about in 

 the water ; swam to the surface ; changed their forms, in a va- 

 riety of ways, on the slightest irritation ; and, when torn under 



