JOHNSTONE, ON BRITISH SF.A-WEKDS. 57 



own peculiar power of reproductive organs, and few objects 

 are more beautiful and more interesting subjects of micro- 

 scopic research at the seaside than these organs amongst 

 the alga?. 



The present volume is only one of four which it is in- 

 tended to devote to the whole of the British Algae. It con- 

 tains sixty-six plates, and embraces only a part of the 

 Rhodospermea, the remainder of which will appear in the 

 second volume. The families illustrated in this volume are 

 Rhodomelacea, Lamenariacece, Corallinacece, Spluerococcoideee, 

 Gelidiacece, Spongiocarpea, Sguamariea, Helminthocladiea, 

 Wrangeliacece . These families are embraced under the divi- 

 sion Desmiospermeae, a group in which the spore-bearing 

 nucleus consists of tufted spore-threads attached to a cellular 

 placenta. The spores are formed singly, one in each cell of 

 the spore-thread, or only one in a terminal cell. 



Many of the species illustrated in this volume are amongst 

 the most elegant and fragile of the algae. We can, however, 

 from a comparison of them with recent specimens at the 

 sea-side, speak of them as exceedingly accurate in their 

 forms, and very close to nature in their colours. There is 

 one group, however, which seems to have defied the nature- 

 printing process, and that is certain forms of the Corallinaceae. 

 These plants creep along over stones and rocks, something 

 in the same way as lichens; and as they cannot be removed 

 without damage from the objects on which they grow, of 

 course nothing was left but to give coloured drawings or 

 engravings of them. This has been done with the genus 

 Meloseira, embracing the various forms of crustaceous algae 

 known by the name of Nullipores. These plants, which 

 were at one time regarded as zoophytes, and even described 

 by the late Dr. Johnstone with sponges, have a great interest 

 for the physiologist, as indicative of the earliest struggle of 

 organic forces with the chemical laws of nature. They still 

 present aninterestingsubject for study, although their vegetable 

 nature has been Avell made out, and the arrangement of their 

 reproductive tissues is found to resemble closely many of 

 the higher forms of the red sea- weeds (Rhodospermece) . 



Although this work is evidently intended for the botanical 

 student already acquainted with the details of the structure 

 of the algae, we think it might be made a more widely in- 

 teresting work if it were accompanied by an introduction to 

 the study of the structure and functions of the algae. We 

 know that a good introduction already exists in Mr. Berkeley's 

 admirable Introduction to the study of Cryptogamic Botany. 

 But this work embraces other things, and has been published 



