THE PLANT-CELL. 



11 



examples of large cells are found in the Thallophytes ; Nitella, 

 ior example, has cells 50 mm. (3 inches) long, and 1 mm. 

 <.04 inch) thick. According to Von Mohl, the bast-cells 

 of a species of palm (Astrocaryum) are from 3.6 to 5.6 mm. 

 (.13 to .31 inch) in length. For ordinary plants the average 

 size of the cells may be given as from .1 to .03 mm. (.004 to 

 .0008 inch). From this average size the dimensions of cells 

 decrease to exceedingly small magnitudes. In the Yeast 

 Plant {Saccharomyces cerevisice) the cells are about .008 mm. 

 (.0003 inch) in diameter. The cells of Bacterium iermo are 

 irom .0031 to .0038 mm. long and from .0038 to .0005 mm. 

 broad (.0001-00008 by .00008-. 00003 inch). 



The following table, taken from Hofmeister's " Lelire von der Pflan- 

 aenzelle," is useful as sliowiag how the dimensions of similar cells 

 vary in different plants : 



Table of Dimbnsions of Various Kinds of Cells of Woody 

 Plants. 



(In dGt;imals of a millimetre.) 





f 3 



SO 



6( 



§3': 



« y 



H " 1 

 & 



*= 5 ; 



H C3 U 





» bo 

 B <a 



■Cambium-cells, avei-age length 



Vessel-like wood-cells, average length 



Bast-like wood-cells, average length , 



Veseel-cells of the wood, average length 



Latticed cells of young secondary bark, aver- 

 age length 



Bast-cells of young secondary bark, average 

 length 



Cells of medullary ray in the cambium ring, 

 maximum length in tangential section 



Do., do., maximum widtn in tangential sec- 

 tion 



Cells of medullary ray in the young wood, 

 average length in tangential secti<m 



Do., do., average width in tangential section. 



Cells of medullary ray in the young secon- 

 dary bark, average length in tangential 



section 



J>o., do., average width in tangential sec- 

 tion 



.301 



.3U1 



.aj5 



.198 

 .321 



.041 



.376 

 043 



.413 



.5i3 

 .404 



.520 



.437 



.ore 



.519 



.077 



.912 

 .066 



.5-^8 

 .'j-is 



.178 

 .011 



.285 

 .019 



031 



1.179 



ieis 



.403 



.838 



.017 



.567 

 .037 



.504 

 .076 



•86 



i.m 



1.511 

 8.030 



1.162 2.183 

 .049 



.056 



.630 

 .075 



.014 



.095 

 .019 



.744 .172 

 .075 .024 



