84 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



ALLIANCE I. 



Algales, Lindl. 



AhGjE, Juss. D. C, Agardh, dec. — THALASSiopnyTA, Lam. — Hydrophtta, 

 Lyngb. — Hydronemate.e, Nees. — HYDROPHYa^, Fries. — Phtc^es, 

 Montagne. 



Cellular flowerless plants, without any proper root or myce- 

 lium, living, for the most part, entirely under water, and im- 

 bibing nutriment by their whole surface, from the medium in 

 which they grow. Propagation of various kinds, sometimes by 

 the mere division of the endochrome, sometimes by spores or 

 zoospores, formed from the endochrome, or by the mixing of 

 two endochromes ; sometimes by the joints of privileged 

 threads, either naked, or contained in especial organs, and oc- 

 casionally of two orders. Sexes often distinct on the same or 

 different individuals ; impregnation, by means of spermatozoids 

 furnished with one or more flagelliform appendages, but obsolete 

 in the lower species ; spermatozoids very rarely, if ever, spiral. 



65. The objects which constitute this large family, are 

 extremely variable in appearance. Many can scarcely be ex- 

 amined as regards their external characters, without the assist- 

 ance of a magnifying glass ; while others form subaqueous 

 forests, or float in dense masses many miles across, the indi- 

 vidual plants of which are sometimes one hundred feet or more 

 in length ; some are devoid of all beauty, while others are^ 

 perhaps, the most elegant objects in nature, alike attractive in 

 form and colouring ; added to which, the markings in the sili- 

 ceous shells of one main division are so exquisite, as to consti- 

 tute them the most admirable objects for the microscope. 



66. The first question which occurs in the consideration of 

 the subject generally, is where the limits of the order are to 

 be sought. It is very clear, that many of the lower species are 

 upon the very confines of the animal kingdom, and in conse- 

 quence, many undoubted Algae have been referred by iiuthors 

 to that division of organised beings. There was, indeed, some 



