CHAP, in.] of Cell-membrane in Plants. 277 



himself, remind us in many respects of von Mohl, though it 

 would be more correct to say that von Mohl's manner reminds 

 us of Moldenhawer, for from the great respect which von Mohl 

 displays for him, especially in his earlier writings, it can 

 scarcely be doubted that he formed himself on Moldenhawer's 

 ' Beitrage,' and first learnt from them the earnestness and care- 

 fulness demanded by phytotomic work. 



It has been already mentioned that the study of vegetable 

 physiology is indebted to Moldenhawer for one important 

 practical improvement. He was the first who isolated cells 

 and vessels by allowing parts of plants to decay in water and 

 afterwards crushing and dissecting them, a process not much 

 used in modern times, though it may still be applied with 

 advantage in conjunction with what is known as Schulze's 

 solution, especially if it is carried out with Moldenhawer's 

 carefulness and circumspection. The isolation of the ele- 

 mentary organs of plants by maceration in water necessarily 

 brought Moldenhawer into direct antagonism with Mirbel, 

 who with Wolff assumed that the partition between any two 

 cells was a single wall ; whereas Moldenhawer found that the 

 cells and vessels were closed tubes and sacs after isolation, 

 and must necessarily, as it would seem, so lie one against 

 another in the living plant, that the wall between every two 

 cell-spaces is formed of two membranous laminae, and he ex- 

 pressly says that this is the case even in very thin-walled 

 parenchyma. This result remained unassailable, so long as no 

 one was in a position to conclude from the history of the 

 development of cell-tissue that the partitions are originally 

 single, or by aid of strong magnifying power to prove the true 

 structure of the walls and their later separation, and the dif- 

 ferentiation of the once single wall into two separable laminae. 

 If the view based on the results of maceration was still not the 

 true view, yet it was nearer the truth as regards the matured 

 state of the cell-wall than that of \Volff and Mirbel, and the 

 important advantage was gained of being able to study the 



