ORCHIDACEARUM GENERA ET SPECIES. 451 



energid invades a cell, forces the nucleus of that cell to retire, draws 

 to itself the protoplasm of the host-cell, and finally subdivides to 

 form new cells in which it makes use of the cell- wall of the host. 

 This is best seen in GlceosipJwnia, where the sporogenous energid 

 takes full possession of the auxiliary-cell, so as to render the original 

 cell-contents unrecognisable ; at the same time causing protube- 

 rances to swell out in the wall of the host. 



Prof. Oltmanns concludes his paper with a comparison between 

 FloridecB and other plant groups, founded on the theory of alter- 

 nation of generations. He likens this parasitism on the part of the 

 sporogenous-filaments to the apparent parasitism of the non- sexual 

 on the sexual generation of mosses ; and draws attention to the fact 

 that the sporogonia of MuscinecB and the sporogenous-filaments of 

 FloridecB are in part able to support themselves. Prof. Oltmanns 

 adds that he does not hold with any sharp distinction between the 

 two generations since fresh investigations may shortly cause bota- 

 nists to change their views on this point ; but he is anxious to show 

 that comparisons may be drawn between the higher groups of 

 Thallophytes and the Muscinece. This does not necessarily mean a 

 relationship, but rather a development on parallel lines. The views 

 of Profs. Nageli and Pringsheim are given on this point, and then 

 the likeness to the Ascomycetes is shown, with references to some of 

 the many writers on the subject. Prof. Oltmanns says : " If a 

 relationship between the FloridecB and the Ascomycetes should ever 

 be proved, that does not in any way remove the difficulty of linking 

 the FloridecB with lower groups of alg?e. That ColeochcEte can 

 scarcely be considered such a link, I have lately tried to show ; and 

 also among other algae I can find no satisfactory connection ; the 

 Floridem must therefore remain for the present as an archetype, 

 using the word in the Sachsian sense." 



Finally, after a very short summary, Prof. Oltmanns winds up 

 his paper with the words : " A double fertilization such as Prof. 

 Schmitz wished to prove does not therefore occur in the Floridese." 



E. S. B. 



Orchidacearum Genera et Species. Exposuit Fritz Kraenzlin. Vol. i. 

 Fasc. 4-8. 8vo, pp. 193-512. Berlin : Mayer & Miiller. 

 1897— July, 1898. 



Fascicles 1-3 of this work were reviewed in this Journal for 

 1897, pp. 493-495, where we drew attention to the unsatisfactory 

 character of the literary side of the work, and other signs of too 

 hasty production. A similar criticism may be made on the parts 

 now before us. We fear that Dr. Kraenzlin has undertaken a task 

 for which, however competent he may be, he has not sufficient 

 leisure to carry through successfully. Orchids are a large family, 

 the genera need careful consideration, and we think Dr. Kraenzlin 

 would have done better to have followed the example which has 

 proved so successful in Engler & Prantl's PJianzenfamilien, and have 

 sought the aid of other botanists. By a judicious distribution of 



