THE 



GARDENER'S MAGAZINE, 



NOVEMBER, 1843. 



ORIGINAL COMMUNICATIONS. 



Art. I. Comparative Physiology. By R. Lymburn. 

 (Continued Ji-om p. 312.) 



On Absorption in Vegetables he says: "In the lowest plants we 

 find this function performed under its most simple conditions. 

 The simplest algce, as Protococcus nivalis, consist of individual 

 cellules, each capable of nutrition and reproduction. The higher 

 conferv£e and sea-weeds consist of masses of cellules united into 

 a leaf-like expansion, which performs the nutritive and repro- 

 ductive functions on all parts of its surface, any semblance of 

 stem and roots appearing only to give the means of attachment. 

 The lichens are similar in form and structure to the sdgse, but 

 the different situation appears to produce a separation in the 

 functions ; reproduction being confined to the upper surface, 

 which from exposure gets hard and dry ; while it is by the lower 

 surface, usually soft and pale, that the nutriment^ is j^robably 

 absorbed, and it is frequently furnished with hair-like appendages 

 resembling roots. The lower groups of fungi seem to imbibe 

 by their whole surface, while the more complex mushrooms 

 have the reproductive system sepai^ated from the nutritive by a 

 stalk, whose base is prolonged into radical fibres, by Avhich, and 

 probably also by the hairs on the surface, the food is introduced 

 into the system. 



" In ascending through the tribes of Cryptogamia the func- 

 tions get more specialised, though when these special organs are 

 undeveloped, or insufficiently supplied, the general surface can 

 supply the deficiency. The whole surface of the radical fibre in 

 Cryptogamia is endowed with the power of absorption, except in 

 ferns, which approach Phanerogamia, or flowering plants ; in 

 which fluid is admitted through the succulent extremity alone, 

 the function being more actively performed in projDortion to the 

 diminution in amount of surface they expose. The simplest 

 form of roots consists of single fibres from the base, as in hya- 

 cinth and other bulbs and tubers ; but more often the fibres joro- 

 ceed from ramifying branches of woody texture, as in trees and 

 3d Sen — 1843. "XI. o o 



