286 On the Hermaphrodite mode of 



but in the green species I have in general seen only two or 

 three, placed alternately on opposite sides of the body. 

 The interior of the capsule has a slightly ribbed or striated 

 appearance, and at the summit a small aperture is sometimes 

 perceptible, through which, when the development is com- 

 plete, the spermatic filaments are observed to issue. In 

 breaking up the capsule, under the microscope large numbers 

 of these filaments are seen united in bundles by their minute 

 globular heads, the filamentous part being free, and vibrating 

 with great rapidity, in the manner which is known to be cha- 

 racteristic of these bodies in all animals. 



I have noticed more than once, when an ovum was developed 

 on the same individual which bore the spermatic capsules, the 

 animal bend its body suddenly round, so as quite to double it, 

 and to bring the spermatic capsules and ovum close together ; 

 and as this is an attitude rarely observed in the polype at 

 other times, I am inclined to regard it as related to the act of 

 self-fecundation. 



The spermatic capsules, with lively movement of their fila- 

 ments, were observed on many individuals in which no ova 

 existed. 



The rounded body, which I have hitherto termed, indiscri- 

 minately, ovum and ovigerous capsule, is, when fully developed, 

 of such a size as to be seen with the naked eye. It is attached 

 to the side of the polype, nearer the foot than the spermatic 

 capsules, and is distinguished from the rest of the animal by 

 its spherical form and yellowish-brown colour. In the Hydra 

 viridis I have never seen more than one of these ova developed 

 on the body of the polype at the same time ; but a number 

 varying from four to seven have been observed by others upon 

 the Hydra fusca. 



This body appears at first as a small granular mass in the 

 thickness of the wall of the animal. A germinal vesicle 

 was not apparent; but as I found it impossible to burst 

 the capsule to examine the contents without injuring them 

 greatly, it may still have existed within the granular mass. 

 As the spherical yolk mass enlarged, it projected from the 

 side, seeming at first to carry along with it the outer or clear er 



