. 























Itf VEGETABLE BIOLOGY. 



515 





Millon 



is shown at 



Plate XIV. fig. 8; here the colour has been discharged, but the 

 protoplasmic reticulum (drawn in the lower cell alone) is still 



visible. 



The limiting layer of protoplasm comes out now very 

 clearly ; it seems to be reflected over the stoppers *, but perhaps 



the 













appearance giving rise to this idea is really due to denser 

 consistence at the boundary of the stoppers ; at any rate the 

 limiting layer also extends over the bed whereupon the stoppers 

 rest. The latter now have a granular look, in sharp contrast with 

 ne uniformly white and apparently homogeneous swollen cell- 

 wall ; the granules are evidently precipitated by the reagent, and 

 the protoplasm itself has much the same granular character. The 

 pit is here very well seen with its broad debouching points, and 

 lie connecting protoplasm also comes out very clearly. 



Another excellent way of studying the relation between 

 stoppers and cell-wall is to use Schulze's macerating fluid. 



this, the cell-contents contract after the stoppers have 



ome invisible. Sometimes only one ball of protoplasm is 



found in the cell, but more often there are several, the sphe- 



ft m / 



bee 





roidal form greatly predominating ; each ball is surrounded by i 

 °wn delicate membrane, and usually the pit is left quite clear of 

 plasma (Plate XIV. fig. 9, b). In other cases, and especially if the 

 action has not been too violent, the connecting protoplasm is still 



) 



thread. When 











. 





■ 







m % 9, a, plasma-balls remain in position at either end of the 

 pit, there is no trace of the stoppers ; the protoplasm of these 

 balls is still reticulate. But the fact of most interest is that on 

 »ow running in iodine, the plasma-balls at once take a fine 

 brown colour— colour which is quite as pronounced in these balls 

 into which the stoppers have melted as it is elsewhere; the 

 cell-walla remain uncoloured by the iodine. 



Oiuam and Classification of the Substance of 



Ballia Stopfehs. 

 On the ground therefore : 



-t» Or tnA GrOTiAiHk.1 n.nrw 



w ground therefore: — . - . 



Of the general appearance of the stoppers, which is so 











2. 



cinterent from tnat oi tne ceu-wau , 

 Of their distinctive proteid reactions, those of the wall 



lmi'nn U„4- ■P/wi'Mtr oTinwn if at all ; 









«-*. i _ 



Thus Archer describes the stoppers as lying outside the primordial utricle 

 (Trans. Linn. Soc. 2nd Series, i. p. 214). 













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