22 Mr. A. H. Hassall on the Anatomy and Physiology 



the two latter being readily accounted for by the disappearance 

 of the radii (PL I. fig. 2 and 3). 



The circumstance of the increased development of the cyto- 

 blastic body, subsequent to the removal of the radii, gives weight 

 to the opinion that this organ has yet another office to perform 

 in addition to that of presiding over the growth of the cells ; for 

 were it not so, it might be expected that on the disappearance 

 of the rays it would shrivel up and at length become absorbed, 

 as is the case with other organs, their allotted duties having been 

 performed ; and the office which I would attribute to it is one 

 even of more importance than that previously remarked upon, it 

 being no other than the fertilization of the brilliant granules en- 

 tering into the formation of the spiral threads, and which I regard, 

 as before noticed, as the unfertilized zoospores. 



But it may be asked, if this be so, what is the purpose of the 

 union of the filaments of the Conjugates and intermingling of the 

 contents of two cells, phsenomena which present themselves so 

 frequently amongst the Confervse ? This question is not un- 

 answerable ; but whether the answer now to be given shall be 

 deemed satisfactory, must depend upon future obseiTation. 



It may be that the combination of the material of two cells is 

 necessary in the cases where true spores are to be found, although 

 it would appear that no such combination is requisite in those 

 Confervse whose sole mode of reproduction, as in the greater pro- 

 portion of the branched species, is by means of zoospores, fertili- 

 zation in these being efiected by means of the organ described in 

 this paper. 



But I must confess, that from circumstances which have re- 

 cently come to my knowledge, and which I hope to be enabled 

 to make the subject of a detached communication ere long, my 

 faith in the existence of a double mode of reproduction, viz. by 

 true spores and by zoospores in some Confervse, has been consi- 

 derably shaken, and my present belief is, that the only method 

 which exists is that by zoospores ; in which case the commingling 

 of the contents of two cells, and the formation of large spherical 

 or elliptical bodies furnished with membranes by such commingling 

 and union, might be thus explained. The combination might be 

 regarded merely in the light of an act of ceconomy on the part of 

 nature, whereby a saving of organization is effected, and the bodies 

 themselves as so many sporangia filled with zoospores. 



The adoption of the view which supposes the fertilization of the 

 reproductive bodies by means of the organ whose complicated 

 anatomy has been dwelt upon, would have the effect of remo\dng 

 some grand difficulties in the way of the complete understanding 

 of these most interesting productions. Thus, first, by furnishing 

 a definite organ whereby fertilization is occasioned, it removes 



