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 TRANSLATIONS. 



Algarum Unicellulakium Genera nova et minus cognita, 



prcemissis Observationibus de Alois Unicellularibus 



in ffenere. 

 Neiv and less known Genera of Unicellular Alg^e, preceded 



by Observations respecting Unicellular Alg,^ in general. 



By Alex. Braun. (Leipsic, 1855 ; wdth six Plates.) 



The author^ after adverting to the important aid to be de- 

 rived from the study of the lowest plants, and especially of the 

 Alga, and more particularly of their evolution, in the advance 

 of our knowledge of the morphology and physiology of plants, 

 and the establishment of a systematic arrangement of the 

 vegetable kingdom, proceeds to some observations concerning 

 unicellular Algce in general, the substance of which is as 

 follows : 



Whether or not unicellular plants really exist, appears to be 

 a question of no light moment towards the understanding of 

 the gradation of Nature in ascending from the lower to the 

 higher organisms, and especially towards the construction of 

 a methodical arrangement of the vegetable kingdom in con- 

 gruity with Nature, whose principles, as well as the correct 

 appreciation of the nature of each plant, are chiefly to be 

 sought in the study of the processes of evolution. 



For our knowledge of the natiu'al system of plants, which 

 is daily increasing, indicates, iu scarcely dubious terms, a 

 parallelism between the primary divisions of the vegetable 

 kingdom and the principal stages of morphosis presented in 

 the development of each individual plant (that is to say, of 

 those belonging to the more perfect class) ; and thus is shown 

 a certain analogy between the vegetable kingdom and the 

 organism of the individual plant, and the prevalence of a 

 similar law of evolution proceeding by steps, in each. 



It is well known that the primary germ and rudiment of 

 the nascent plant is a homogeneous and indifferent substance, 

 presenting scarcely any diflerences either in external form or 

 internal constitution. In phanerogamous plants this is ap- 

 parent in the formation of the embryo sac,* which is ulti- 

 mately changed into the substance of the endosperm, and to 



* That the embryo sac is the commencement of the future plant, besides 

 by analogy, is proved by its nature, inasmuch as being disconnected from 

 the parent tissues, and destroying by its own growth the texture of the 

 surrounding cells, it leads as it were a parasitic life withiii the parent plant. 



