202 Dr Martin Barry on the 



bryology put into my hands by the revered President of 

 this Society, Professor Jameson. 



The nucleus of the vegetable cell had long been noticed 

 before it received any particular attention, which was first 

 given to it by our distinguished fellow-countryman, Robert 

 Brown ; who states this body to have been so neglected, that 

 there are instances of botanists having actually figured the 

 nucleus in the cell, without thinking it worth noticing in 

 the explanation of their plates. The structure in question 

 did not obtain the attention of physiologists in general 

 until the year 1838, when Schleiden published his obser- 

 vations on the nucleus of the vegetable cell; which ap- 

 pear to have given rise to, — for they were immediately fol- 

 lowed by, — the extensive and invaluable researches on cells 

 in animal tissues, by my friend Professor Schwann. And 

 never, perhaps, did the microscope yield a richer harvest of 

 observations than on that occasion in his able hands ; for to 

 Schwann we are indebted for the great discovery, that the 

 elementary parts of tissues have a like origin in cells, how- 

 ever different the functions of those tissues. It is with re- 

 gret that I place his name in the list of those from whose ob- 

 servations on cellular development my own widely differ, — the 

 differences relating to points of cardinal importance. 



Schleiden shewed the nucleus to be the part that gives 

 origin to the membrane of the cell, which membrane when 

 in an incipient state he compared to a watch-glass on a 

 watch. But Schleiden supposed that when the nucleus has 

 given origin to the membrane of the cell it has performed 

 its office ; and that, not being further required, the nucleus 

 then either remains inert in the cell-wall, or is " cast off as 

 a useless member," and " absorbed.'- I am not aware that 

 that opinion of Schleiden was questioned in any quarter, 

 until my own observations had shewn it to be the very 

 opposite of the truth. So far from the nucleus of the cell 

 either remaining inert in the cell-wall, or being absorbed as 

 useless, it is a most active agent, and endowed with proper- 

 ties of the first importance ; while the membrane it forms is 

 a structure subordinate thereto. 



