THE SKELETON OF THE PLANT 39 
ment of the supporting and conducting tissue at an early 
stage of its life, and the latter indicates the condition 
after several months, during which a large formation of 
secondary vascular tissue has taken place. 
The structure of a coenocyte shows a similar mode of 
formation of the skeleton to that of 
a woulticellular plant-community. 
In this case, however, the several 
protoplasts are not furnished with 
separating walls. The only skele- 
ton is the external membrane which 
limits the whole structure, and 
which is formed by the conjoint 
activity of them all. In compound 
or septated ccenocytes we have in 
addition certain transverse walls 
crossing the interior and giving a 
greater degree of strength to the 
whole body. These separating 
walls have a similar origin. 
The primary cell-wall which 
clothes the unicellular plant, and 
which serves as the original sup- 
porting membrane of the separate 
protoplasts of a community or 
colony, is, when first formed, a 
clear, transparent, extensible, and 
elastic membrane, which remains 
in contact with the protoplasm so P%%. 41—EMRRyo or Orobus 
. at AT THE END OF A LONG 
long as the latter is living. Under Svusrzyson, Tue two Sze- 
i Stas, ‘6 i MENTS OF WHICH HAVE A 
certain conditions it is capable of Canocyric —_ StructuRE 
heorbine eonsiderabl titi (After Guignard.) 
3 ‘ 8 ey a The rounded bodies in the seg- 
of water, and in consequence swell- ments of the ccenocytes are 
: the nuclei of the protoplasts. 
ing to a greater or less extent. 
Under ordinary conditions it is freely permeable by 
water. It is usually said to be composed of a sub- 
stance termed cellulose, whose chemical composition is 
