226 PHYSIOLOGICAL BOTANY. 



of Allium porrum, because in the garlics the spherical 

 clear bodies exist, which exhibit an appearance of one 

 cell within another, and have sometimes confirmed ob- 

 servers in the belief that the young cells were contained 

 within the old ones. We shall call them the secondary 

 cells. On making longitudinal sections parallel with, 

 or even perpendicular to, the surface of either the upper 

 green portion or the under colourless part of the leaf, 

 and examining them in a drop of water in the usual way 

 with a sufficient magnifying power, we perceive in the 

 white part the light cells, which appear clear and trans- 

 parent ; in the green part, we see here and there a little 

 of the granulo-cellular matter, which most of the cells 

 contain, and we also find the light, globular, secondary 

 cells. But if the sections are moistened for a few minutes 

 with nitric acid, and then washed with water and coloured 

 with tincture of iodine, the whole is changed. We now 

 see, inside the cells, a sac of a yellowish colour, and 

 almost of the same form as the cells, but more or less irre- 

 gular, frequently lacerated, more or less detached from 

 the wall of the latter, and also more or less contracted. 

 It is completely filled with the granulo-cellular matter, 

 and when secondary cells are present they are scattered 

 within the sac, more deeply coloured than the sac of the 

 cell, and completely filled with granules. The external 

 membrane of the cell remains transparent, and perfectly 

 un coloured. But the most remarkable feature exists in the 

 small warty projections on the margin of the sac, which 

 fit into apertures in the external membrane of the cell ; 

 between them this membrane appears raised in roundish 

 portions, and sometimes we perceive obscurely-defined 

 laminae in these tumid spots. 



After these experiments, I must express my approval 

 of Hartig's memoir upon the Structure of the Vegetable 

 Cell. The membrane of the utricle is evidently his 

 Ptychode, a membrane which descends into the so-called 

 pores of the external membrane, and is really a distinct 

 membrane ; it surrounds the internal contents, but 



