INTRODUCTION. 31 



Since the above observations were written*, my attention 

 has been directed by Mr. Francis to a lecture by M. Morren, 

 inserted in the " Bulletin de 1' Academic Royal des Sciences 

 de Bruxelles," for 1837, from the perusal of which it 

 appears that the growth of many Confervas, by the division of 

 the cells has been noticed by more than one observer. From 

 this lecture I make the following extracts : 



"In 1832, M. Dumortier published his memoir upon the 

 structure and developement of plants and vegetables, in which 

 he established with the greatest clearness the fact of the 

 increase of a number of cells by division. His researches 

 were carried on upon Conferva aurea, in which the terminal 

 cell elongates itself more than the others, in order to form in 

 its interior an intermediate production (partition), which 

 divides the cells into two parts, each becoming a new cell." 

 No one could be more explicit, observes M. Morren, who 

 goes on to say, "the division of cells by intermediate membranes 

 was examined likewise by M. Hugo Mohl in September 

 1835, upon Conferva glomerata, &c., a terminal cell of which 

 showed near its centre the commencement of a diaphragm 

 proceeding from the circumference towards the centre." This 

 is in all respects, M. Morren remarks in continuation, the 

 observation of M. Dumortier, but upon another species, and 

 it is all simply the fact previously noticed by myself upon 

 Cruciagenia, but transported from the Diatomacece to the 

 Conferva. 



From this it appears that M. Morren would claim for 

 himself priority in the discovery of the increase of cells of 

 Conferva by division, but the single observation published 

 in August 1830, upon the genus Cruciagenia., an Alga 

 differing much in structure from true Confervoid productions, 

 would hardly suffice to establish for M. Morren this claim 

 any more than would the observation of Mirbel on the 

 division of the pollen cells give him a claim to the discovery 



* The substance of the preceding remarks, on the growth of the Alga, 

 is extracted from a portion of an " Essay on the Confervas," read before 

 the Dublin Natural History Society and inserted in the " Annals and 

 Magazine of Natural History," vol. i. p. 431. 



