RHIZOGENS. 85 



total want of spiral vessels. That, however, was a mistake. Spiral vessels 

 do exist among them. Brown says that he has discovered them in Rafflesia, 

 in which he originally failed to perceive them, and in several other cases. 

 Martins also found them in Langsdorffia, in the form of bundles lying in the 

 rhizome, stem and branches, and Mold in similar parts of Helosis, but in 

 small quantity compared to the mass of the plants. Brown adds that " the 

 vascidar system of all these parasites is uniform and more simple than that 

 of the far greater part of Phfenogamous plants ; that the spiral, or slight 

 modifications of it, is the only form of vessel hitherto observed in any of 

 them ; and that the large tubes or vessels, with frequent contractions, 

 corresponding imperfect diaphragms, and variously marked sm-face, which 

 have received several names, as vasa porosa, punctata, vasiform cellular 

 tissue, dotted ducts, &c., and which are so conspicuous in the majority of 

 arborescent Ph^enogamous plants, have never been observed in any part 

 strictly belonging to these parasites. [Linn. Trans, vol. xix. 231.) He, 

 however, does not attach systematical importance to this curious fact. 



The flowers are in general formed upon some symmetrical plan, the pro- 

 portions varying from genus to genus. But in a singular deformed genus 

 called Sarcophyte the flowers are not reducible to symmetry, as far as has 

 yet been observed. It has not, however, been examined in a j^hilosophical 

 manner. 



The seeds of most Rhizogens appear to have baffled the inquiries of those 

 who have had the best opportunities of examining them. Even the seeds of the 

 common Cytinus Hy]30cistis of the South of Europe are wholl}^ unknown ; to 

 the disgrace of Mediterranean Botanists. Blume describes the seeds of 

 Brugmansia Zippelii as containing, 1° a grumous substance which under a 

 powerfid microscope exhibits a lax cellular tissue, formed of roundish cells, 

 which become angular by mutual pressure, and are filled with grumous 

 matter ; among these are dispersed, 2° threads or tubes, very numerous, very 

 tender, long, entangled without order, usually forked, sometimes irregularly 

 branched. Upon these threads Blume makes the following remarks : — 

 " The tender tubes, principally visible in the ripe spores of Rhizogens, may 

 be considered analogous to those lowest forms of vegetation which belong to 

 the genus Mycoderma, Pers., of the family Hydronemateie. The parietes of 

 the fruit of Brugmansia are seldom covered with spores when the pericarp 

 is closed up, but they constantly are when the plant is decaying : a circum- 

 stance which is attributable to the facility with which the spores separate 

 from their stalks, and to the cellulo-gelatinous matter in which the fruit 

 abounds. It is worthy of remark, however, that the spores are attached in 

 the same manner as the seeds of more perfect plants, although they are 

 altogether different from them in structure. They are, indeed, to be com- 

 pared only to the unfecundated ovules of Phsenogamous plants, which in the 

 latter are more completely evolved after impregnation, but in Rhizogens, as 

 in other Cryptogamous plants, only after germination. That the ovules of 

 Rhizogens, while inclosed in the pericarp of their mother, ever arrive at the 

 development of an embryo, seems to be altogether untrue. For I have over 

 and over again examined numerous specimens at different stages of forma- 

 tion ; the observations have been repeated under the eyes of Reinwardt, 

 and the brothers Nees von Esenbeck ; as also by Meyen, so celebrated as 

 an anatomist, upon specimens preserved in spirits of wine, so that I can 

 deny the possibility of any error. How, indeed, can we suppose Rhizogens 

 to be plants furnished with an embryo, Avhen they exhibit only the simplest 

 form of cellular organization in alftheir parts." [Fl. JmcE, RhiscmthecB, 



