6 INTRODUCTION. 



convej^ed, by means of the tubular radii, to those organs by 

 which the materials are to be assimilated. 



The cytoblast, therefore, is at first fixed in the centre of 

 the cell by the ^prolongations which proceed from it : but it 

 happens, that at a certain ej)och these radii disappear, and 

 then the cytoblast floats freely within the cavity of the cell ; 

 the disappearance of the rays, the cessation of the growth of 

 the cells, and the assumption of the characters of reproduction 

 being almost contemporaneous, or, at any rate, events imme- 

 diately consecutive on each other, and the two latter being 

 readily accounted for by the disappearance of the radii. 



The circumstance of the increased developement of the 

 cy toblastic body subsequent to the removal of the radii, gives 

 Aveight, to the opinion that this organ has yet another ofiice 

 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 ofiice 

 which I would attribute to it, is one even of more imi^ortance 

 than that previously remarked upon, it being no other than 

 the fertilization of the brilliant granules entering into the 

 formation of the spiral threads, and which I regard, as before 

 noticed, as the unfertilized 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 removing some grand difliculties in the way of the 

 complete understanding of these most interesting productions. 

 Thus, first, by furnishing a definite organ whereby fertiliza- 

 tion is occasioned, it removes the inability wliich has hitherto 

 been felt to explain in what way the intermingling of bodies, 

 in all respects so similar in organization and appearance as 

 the bright granules of the Conferva seem to be, can be re- 

 garded as giving origin to fertility : secondly, it does away 

 with the anomaly, which has always appeared to me so strange, 

 that a combination of the matter of two cells should iuA^ari- 

 ably take place in certain divisions of the Confervoid tribe of 



