184 NATURAL SYSTEM OP PLANTS. 



date, including those of Endlicher, who was De Jussieu's great successor, Brogniart, 

 and Lindley. 



The difficulty, at the present day, is to make a good selection, and more particularly 

 in a work of this nature, which is to be the handbook of botany to so many thousands 

 of readers both scientific and non-scientific. Our aim must be to obtain that which, 

 with simplicity, will give the most recent and the most valuable information. On 

 careful consideration we are of opinion that we shall be doing an injustice to our 

 readers, if we fail to make them acquainted with the last one above-mentioned the 

 system of a distinguished countryman, which, as it is based upon most extensive and 

 usually accurate information, is deservedly supplanting others in the botanical teaching 

 of the British schools. 



THE NATURAL SYSTEM, ACCORDING TO DR. LINDLEY. 



Before commencing an examination of this system we must beg our readers to bear 

 in mind that a close attention is necessary to the minute parts of the plant, and more 

 particularly of the seed; since, of all organs, that is one possessed of the greatest degree 

 of constancy. We must also give some degree of encouragement to the student by 

 stating, that although this system is not so simple as that previously described, it is 

 yet less difficult than it appears to be. Its difficulty lies at the threshold ; and to 

 overcome it the student will have the gratification of gaining much interesting 

 information. 



We cannot enter at length into the subject, but shall give an outline of the whole 

 scheme, and such illustration as may be interesting and useful to the reader, and 

 necessary to a comprehension of so extensive a subject. The following is a conden- 

 sation of Professor Lindley's scheme (" Vegetable Kingdom," p. lv., et seq.) 



CLASSES. 

 Asexual, or Fkwerless Plants. 



Stems and leaves undistinguishable I. THALLOGENS. 



"A Thallus Is a fusion of root, stem, and leaves, into one general mass, and Thallogens are 

 also destitute of flowers ; they are equally without the breathing pores, so abundantly 

 formed in the skin of more complex species ; and they multiply by the spontaneous forma- 

 tion in their interior, or upon their surface, of reproductive spheroids, called spores." 



Stems and leaves distinguishable 11. ACROGENS. 



*< Beyond Thallogens are found multitudes of species, -which, like Thallogens, are not fur- 

 nished by nature with flowers, but which otherwise approach closely to the higher forms 

 of structure, occasionally acquiring the stature of lofty trees. They have breathing pores 

 in their skin ; their leaves and stems are distinctly separated ; in some of them those 

 spiral threads, which form so striking a portion of the internal anatomy of a more perfect 

 species, exist in considerable abundance ; and finally, they multiply by reproductive sphe- 

 roids or spores, either formed without the agency of sexes, or, if the contrary, shall be 

 proved at all events not possessing bodies constructed like stamens on the one hand, and 

 embryos on the other. Their stem, however, does not increase in diameter ; it only grows 

 at the end, and hence it has given to such plants the name of Acrogens." 



