and on Gemmation in the lower tribes of Plants. 313 



during the very early or embryonic condition of the more com- 

 plicated structures ; whilst a comparison with these latter may 

 serve best to show us the true nature of certain phsenomena con- 

 nected with the development of those simpler organisms. 



The Palmellece have generally been looked upon by botanists 

 as occupying the lowest place in the vegetable kingdom, and on 

 this account any new fact connected with their mode of growth 

 is of peculiar interest. These simple plants generally appear as 

 gelatinous masses of an irregular form, and, viewed under the 

 microscope, as consisting of a number of similar cells imbedded 

 in a gelatine ; these cells having no essential organic connexion 

 with each other, but being merely held together by the gelatine 

 with which each is surrounded. In the opinion of some physio- 

 logists, each of the cells, on account of its possessing an inde- 

 pendent vitality and seeming capable of performing all the func- 

 tions necessary for the growth and reproduction of the species, 

 is to be regarded as representing an individual plant. If, how- 

 ever, we adopt this view of the matter, we must suppose 

 every process of fissiparous division taking place in the cells as 

 a true reproduction of the species, which surely cannot be the 

 case, as will be endeavoured to be shown. 



In the gelatinous masses of the Palmellece numerous branched 

 filaments are found to occur ; these have been figured by Professor 

 Kiitzing in his 'Tabulse Phycologicse*,^ as pointed out to the 

 writer by Mr. Berkeley ; and they have been described by Mr. 

 Hassall in his 'British Freshwater Algae f/ but neither of these 

 two authors seems to have understood the real character of these 

 filaments. Mr. Hassall remarks that they "may either be parasitic 

 growth, or else form part of the organization of the frond ; and 

 in the latter case they may be presumed to be connected with 

 respiration.^' To the researches of Mr. C. E. Broome, however, is 

 due the discovery of their true nature. When examining in 

 January last some portions of a mass of Palmella botryoides, 

 Greville, this excellent observer found that the cells, in an early 

 stage of the plant, are attached singly to the extremities of 

 branched tubular filaments, which are filled with endochrome, 

 and are attached to and radiate from a central large cell of 

 irregular shape (PI. X. fig. 1) ; that the cells subsequently become 

 detached, and each is then seen situated at the end of a mucous 

 prolongation (PI. X. fig. 2) such as is described and figured by 

 Mr. Hassall J in some species of this natural family. 



The writer has been enabled to confirm his friend Mr. Broome's 

 interesting discovery by detecting the attachment of the cells to 



* Tab. Phycologicse, tab. 19. iv., 21. v., 24. i., 25. i. & v., 26. i. & ii. 

 t Brit. Freshw. Algie, p. 318. % Ibid. p. 323, tab. 80. 



Ann. ^ Mag. N. Hist. Ser. 2. Vol. ii. 22 



