538 



FORMAT rON OF MEDUSA-BUDS IN CORYNE. 



leisurely manner. The Fresh-water genus Cordylophora has as 

 yet been only found in a few localities ; and the chief interest 

 attaching to it is derived from the fact of its having been made 

 Fig. 276. * ne su ^ject of an ad- 



mirable Memoir by 

 Prof. Allman, * to 

 which every one should 

 refer who desires to 

 acquaint himself with 

 the minute organiza- 

 tion of this group of 

 Zoophytes. 



414. The phenomena 

 of the Reproductive 

 process exhibited by 

 these Hydrozoa, are 

 extremely curious. In 

 Coryne and its allies, 

 besides the ordinary 

 Gemmation which ex- 

 tends the original 

 fabric, certain G-emma? 

 are developed, which 

 gradually come to pre- 

 sent an organization 

 altogether comparable 

 to that of the simpler 

 Medusa (Fig. 276, b), 

 and which, when de- 

 tached, swim freely 

 away. These stand in 

 the same relation to 

 the ordinary Polype- 

 buds, as the Flower- 

 buds of a Plant do to 

 its Leaf -buds ; each 

 Medusa-bud contain- 

 ing either male or 

 female Sexual organs, 

 and performing its 

 part in the Sexual 

 act, after it has been 

 set - free from the 

 polype-structure that bore it, just as the male (or Staminiferous) 

 flower of the Vallisneria spiralis discharges its pollen upon the 



Development of Medusa-buds in Syncoryna 

 Sarsii:—A, an ordinary Polype, with its club- 

 shaped body covered with tentacles :— b, a 

 Polype putting-forth Medusan gemmse ; a, a 

 very young bud ; b, a bud more advanced, the 

 quadrangular form of which, with the four 

 nuclei whence the cirrhi afterwards spring, is 

 shown at d; c, a bud still more advanced. 



* 'On the Anatomy and Physiology of Cordylophora,' in "Philosophical 

 Transactions," 1853. 



