CELLULAR TISSUE. 13 



examples of numberless anomalies, which the impulse 

 of vegetation occasions in the form of cellules. PoUini 

 has particularly insisted on the variety of the form of 

 the cellules in one and the same organ. 



The cellules which are termed round or hexahedral, 

 compose the cellular tissue called regular, that is to 

 say, which is not perceptibly lengthened in one direction 

 more than another. These cellules compose the pith of 

 trees, the cellular envelope of the bark, the flesh of 

 pulpy fruits, the parenchyma of leaves, and, in general, 

 all the parts of plants which are susceptible of little or 

 no elongation. 



The Tissues which Link describes under the names 

 of Globular, Vesicular, or Irregular, appear to me to 

 be modifications of that which we here name Round 

 Cellular Tissue. 



This round cellular tissue is destined, according to 

 Link, to preserve and to elaborate the sap. Dutro- 

 chet assures us, on the contrary, that sap is not 

 usually found here. The difference between these two 

 assertions, resides probably in the meaning which is 

 attached to the terms : if it is understood by the sap, the 

 juice not yet elaborated, and which is proceeding to the 

 fohaceous organs, there to receive the action of the air 

 and light, it is consistent with truth to say that the round 

 cellules do not contain any of it : if the word sap is used 

 to express a juice which has already undergone some 

 elaboration, or which is placed in a situation to receive 

 it, in that case we can say that the cellules contain this 

 juice; and what happens in the parenchyma of fruit 

 during their maturation, seems to me to prove it. 



Cellules elongated in a longitudinal direction, (PI. 1, 

 fig. 7) are sufficiently different from the precedmg, and 

 even sometimes come nearer in their form to true vessels. 

 Mirbel described them first under the name of Little 



