358 PHYTOXOMY. 



to the type of the family or species. The germinating 

 mosses thus produce conferva forms, which often remain for 

 a long time after the young ]\Ioss has attained its full size ; 

 (Nees, de Muscorum propagatione Dissertatio.) Germinating 

 Ferns and Alga* produce lobed cellular forms, which remind 

 us of the structure of the Musci hepatici, and which are im- 

 properly named Cotyledons, since the existence of these can- 

 not be suspected or proved in 4:he seeds of these lower organic 

 bodies. We have formerly shewn, that in the Naiadae and 

 in some other families, the thickened cotyledonous end of the 

 germ, and, in the Pahna? and Junceae, the lateral tubercles, 

 furnish the apparatus, by the help of which the further evo- 

 lution of the embryon takes place. In the Scitamineae and 

 in the Grasses, the vitellus or the scutellum are the organs 

 by which the sap, when prepared, is conducted to the embry- 

 on, and by which its evolution is favoured. 



We must here also, as in most of the lower families, take 

 into account the sheath of the root, or the warty promi- 

 nences from which the radicle first proceeds, and which are 

 equally instrumental in preparing the evolution of the germ. 



These warts, or club-shaped appendages, attract also, in 

 higher plants, the moisture of the earth, and push the radicle 

 from the umbilicus. This is always the first external ap- 

 pearance which indicates the germ. The distinction which 

 Claud Richard makes between Endorrhizes and Exorrhizes, 

 is in so far correct, that in the former, the entire embryon not 

 being developed, the roots are first formed from the warty 

 substances ; while the latter, on the contrary, possess a root 

 already formed ; but this also urges on the roots and warts, 

 by which it is succeeded ; (Link, Anatomic der Pflantzen.) 



Plumula? and radicles are separated by what is called the 

 Knot, which constitutes the partition between the descending 

 and ascending motion. From the knot sap-vessels pas§ into 

 the cotyledons. These take up the sap from the radicle, 

 and prepare it, by means of the processes for respiration, 

 with which they are furnished by the slits in their epidermis. 

 From them the sap proceeds, apparently through the same 

 sap-tubes, but at different times, back again to the upper 



