THE SPONGIOLES AND SUCKERS. 83 



lax tissue enjvoys its hygroscopic property in the liighest 

 degree. 



2d. That they perform a very marked degree of ab- 

 sorption without any peculiar visible organization. 



3d. Moreover, that they absorb* the colouring parti- 

 cles of fluids ; while these particles never pass through the 

 stomata, which are infinitely larger than any of the pores 

 with which the surface of the spongioles is provided. 



This last circumstance is moreover very remarkable, 

 when we consider that the colouring particles pass through 

 the close, compact, and almost stony tissue of the surface 

 of the hardest seeds ; and do not penetrate leaves, the 

 tissue of which is so loose, and furnished with pores, 

 very visible under the microscope, and which most 

 assuredly absorb, at least in certain cases, the water with 

 which they may be in contact. This example, among 

 many others, proves to us how even the most delicate 

 anatomy is far from making us acquainted with the inti- 

 mate nature of organized tissues. 



We must, perhaps, class with the Spongioles, the 

 extremities of the Tufts, or Root-like Hairs, which are 

 observed in several lichens; and perhaps also the ab- 

 sorbing extremities of certain Suckers — as, for example, 

 in the Dodder. These are points to be cleared up, and 

 which I leave to the examination of anatomists. As for 

 the analogy of radical hairs with the spongioles, we 

 shall speak of it shortly. 



Suckers (haustoria; 5^<fo^rsj are kinds of tubercles, 

 which spring from the side of the stem of some para- 

 sitical plants, as the Dodder (CuscutaJ ; and are destined 

 for the purpose of absorbing nourishment from the 



* Kieser asserts that the colouring particles only enter into the roots 

 when their extremities are cut off: I know that in this case their absorp- 

 tion is much easier ; but I have seen some roots, plunged into coloured 

 water, absorb red particles, and become coloured internally, in cases where 

 I could not suppose any rupture of the tissue to exist. 



g2 



