16 CELLULAR TISSUE. 



creases in size by the deposition of foreign matter, and by this 

 means, attains a size much greater than its original dimen- 

 sions. The elementary fibre of some of the lower orders of 

 vegetables assumes a different and more varied arrangement 

 than is generally the case in the higher orders. We cannot 

 better give an idea of this arrangement, than by quoting from 

 a memoir of Montague, read before the Academy of Scien- 

 ces, of Paris, in 1837, on the structure of the Caulerpa Web- 

 biana : " In examining, by a compound microscope, a thin 

 slice obtained by a transverse section of the creeping stem of 

 the Caulerpa Webbiana, I saw that there sprung from the in- 

 ternal face of the tube a great number of fiexuous filaments, 

 transparent, continuous, slightly swelled at their origin. — 

 These directed at first transversely anastomosing among 

 themselves, and with those of the neighboring inferior and 

 superior layers, in a manner to form an inextricable net- 

 work. The network is not confined to the creeping root or 

 to the principal frond, but continues to the highest branches. 

 The filaments are smaller the farther they extend from the 

 main body of the plant. In the extremities they do not ex- 

 ceed 1.30,000 of an inch in diameter, while at their origin 

 they are three times as large." According to Schleiden, the 

 formation of fibre never takes place independently of mem- 

 brane. 



8. Organic Mucus is a substance which has but recently 

 assumed a place among the elementary forms of vegetable 

 matter. But from the various researches of Mohl, Brong- 

 niart, and others, it has been demonstrated to be in many ca- 

 ses, a primitive condition of vegetable substance. It exists in 

 the form of a thin homogeneous membrace, covering the cuti- 

 cle of many plants, and forming a lining to the intercellular 

 passages, or filling them up. It probably exists in all plants, in 

 some form, if in no other than forming the cement by which 

 the tissues are made to cohere. In the young shoot of the 

 Sambucus nigra it is readily observed. Meyen considers the 

 intercellular mucus a secretion of the cells themselves. The 

 subject is of recent date, and more investigations will no doubt 

 establish the true nature and functions of the Organic Mucus. 



Section 1- — Cellular Tissue^ 



9. In its most common form it is composed of minute cells 

 or little bladders, and in the living plant in a state of greater 

 or less adhesion, and although the walls of the cells, when cut 

 through, appear to be simple membrane, yet, in some cases, 



