402 IIOFMEISTER, ON 



expanded cells which occurs in so many monocotyledons 

 and dicotyledons is altogether wanting in the Coniferae. 



The mother-cells remain during the winter in the state 

 described. At the commencement of the warmer season 

 the connexion between the mother-cells is dissolved. This 

 occurs in Pinus sylnestris at the beginning, and in 

 P. mariiima in the middle of April. The membranes of 

 these cells become thickened, and one or two of the 

 nucleoli have increased in size. In Pinus balsamea this 

 growth is far more considerable than in Pinus sylvestris, 

 where sometimes all traces of the nucleoli have already 

 disappeared. The fluid substance of the nucleus coagu- 

 lates very easily under the action of water, even more 

 rapidly than in Tradescantia. The viscid fluid contents of 

 the cell then appear most clearly distinct from the spherical 

 cavity, which was filled by the nucleus before the latter 

 became coagulated and contracted into a spherical ball. 

 In Pinus Larix the slight tendency of the cell-fluid to 

 absorb water and become swollen — which is the cause 

 of the appearances above mentioned in P. balsamea — 

 exhibits itself in a different manner. The membrane of 

 the mother-cell swells rapidly in water, and is lifted away 

 from the cell-contents, the original volume of which is not 

 increased. 



The dissolution of the nucleolus or nucleoli soon ensues, 

 as well as that of the nucleus, just in the same way as in 

 Tradescantia, Lilium, Iris, Passiflora, &c. In the homo- 

 geneous fluid contents of the cell, two large flattened 

 elliptical nuclei are next formed. The fluid substance of 

 the latter refracts light in almost exactly the same manner 

 as the fluid contents of the cell, from which it can only be 

 distinguished with much difficulty. At their first appear- 

 ance these nuclei never contain nucleoli (PI. LIX, figs. 2 — 4). 

 Nucleoli — especially in Pinus balsamea — are first produced 

 at a later period, contemporaneously with the distinct defi- 

 nition of the limits of the cell-fluid. These nucleoli are 

 always very numerous, sometimes there are as many as twenty. 

 The nucleoli produced from the nucleus of a ruptured 

 mother-cell of P. balsamea were coloured blue by diluted 

 tincture of iodine, proving themselves to be starch- granules. 



