132 



PLANT ANATOMY. 



nified and have pitted walls. They are 

 often yellowish in color, but not always. 

 They may be distinguished from bast 

 fibres by being shorter and having round 

 instead of oval pores. In the fruit of 

 Pears, Pepper, Pimeata, and barks of 



Fin. ^.—Surface flection "of !FoenugreeVtseed, 

 shovvinu thick»*ned walled stone cells. (Ttfchirch.) 



Cinnamon and Oak the more regular 

 types are to be found. In the seed coats 

 of Physostigma, Abrus, Ricinus and 

 Croton more elongated types may be 

 found, while in tea leaves irregular types 

 occur. Sclerotic colls are best isolated 

 by means of Schultz's maceration fluid 

 when they can be studied to better ad- 

 vantage, 



Collenchymatic Tissues. These tissues 

 consist of cells that are of an intermedi- 

 ary type. They often serve two func- 

 tions, those of mechanical support and 

 the transmission of fluids by osmosis. 

 Hence their walls are thickened at the 





I 



angles, leaving the remainder thin and 

 capable of transmitting fluids. By the 

 juxtaposition of several angles there is 

 formed a strong band which serves as a 

 mechanical support. This is the me- 

 chanical tissue of young, growing parts, 

 and is generally the first kind that is de- 

 veloped. It is absent in most Mono- 

 cotyledons, but is widely distributed in 

 Dicotyledons, being found in the stems 

 and leaves and petioles of most young 

 herbs. In official plants it is found in 

 stems of Coniiim, Levisticum, Malva, 



Mentha, in leaves and petioles of Laurel, 

 Mentha, Senna, Conium, Tussilago and 



in the flower stems of Malva, Sambu- 

 cus, etc. 

 Bast Fibers. (Schlerenchyma in a 



•*j-^* 



Fig. 40.— Collenchyma cells in stem of Umbel- 

 liferous plant, fp, epidermis, ch. chlorophyll 

 grains, con. collenchymatic thickening. 



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atSls *^(Vo^Hoetod)?™ °^™^' ''■ '""'^^^ sections, e. ends, v. dislocations, {. lumen, s. fine stri 



