258 



ABSORBING SYSTEM. 



the cells of the strands are thin-walled, and remain permanently 

 capable of division ; they cut off segments on both sides at such a rate 



that the elongation of the strand keeps 

 pace exactly with the radial expansion of 

 the root. 



After thus dealing with the absorbing 

 system of saprophytes and parasites, we 

 may devote a few words to the mechanism 

 of absorption in carnivorous plants. 133 In 

 certain instances (e.g. Sarracenia, according 

 to Balatin and Goebel) the nutrient solution 

 produced by the digestion of the captured 

 animals is taken in through the general 

 surface of the organ which serves as a trap, 

 just as in the case of hairless roots. In 

 other instances it is probable that the diges- 

 tive glands act secondarily as organs of 

 absorption (Drosophyllum, Dionaea, Pingui- 

 cala). A few carnivorous plants, finally, are 

 provided with special organs that serve, at 

 any rate in the first instance, for the 

 absorption of the products of digestion. 

 According to Goebel, this advanced con- 

 dition is exemplified by Utrimdaria vul- 

 garis. The bladders of this plant bear on 

 their inner surface peculiar four-armed 

 absorbing hairs ; the arms, which resemble 

 root-hairs in form, are filled with oil -drops 

 when the bladder has been recently " fed." 

 The structure of such an absorbing hair is 

 illustrated in the adjoining figure (Fig. 104). 

 Two of the arms are considerably shorter 

 than the other pair, and also diverge more 

 strongly. Each arm consists of a single 

 cell, continued below into a very narrow downwardly directed process 

 with a relatively thick outer wall. These basal prolongations are fused 

 to form a short and slender stalk, which probably serves as a hinge 

 endowing the hair with a certain amount of flexibility and thus 

 preventing it from being damaged by the struggles of the animals 

 caught in the trap. The stalk expands below, where it rests upon 

 a very thin-walled disc-shaped cell (the " intermediate cell " of Goebel), 

 which in turn is seated upon the embedded basal cell or foot of the 

 hair. 



Absorbing hair of Utricularia vul- 

 garis. A. Surface view. B. Vertical 

 section. 



