io NATURAL SCIENCE. Jan., 



had become corky, while on the surface of the young shoots and tubers 

 layers of cork cells were being formed. Mr. Peirce also found that 

 the roots of seedling peas would penetrate the external tissues of 

 branches of an Impatiens, a leaf of Echeveria, a leaf-stalk of rhubarb., 

 a leaf of an aloe, and a stem of a Euphorbia. 



Apospory in the Hart's Tongue. 



As our readers are aware, one of the most interesting phenomena, 

 of plants is the occurrence of an alternation of generations. In higher 

 plants, such as the flowering plants, this alternation is so far reduced 

 that the intermediate generation is a mere rudiment ; but in many 

 lower plants, such as the Ferns, the alternation is complete. In a 

 typical fern, the conspicuous plant as we know it is the asexual or 

 vegetative generation. It produces in due course a number of spores,, 

 the organs in which these are formed being the brown spots on th& 

 under surface of the fronds. Each spore when ripe is discharged 

 from the fern and, if it falls on suitable soil, produces the inconspicuous, 

 prothallus, or sexual generation. On the prothallus, male and female 

 cells are produced in definite organs, and from the union of such 

 male and female cells arises again the conspicuous sexless generation.. 



But in some cases the phenomenon known as Apospory occurs- 

 In such, the sexual generation is produced directly from the tissues- 

 of the asexual generation without the intervention of a spore. In the 

 last issue of the Linnean Society's Journal (vol. xxx., no. 209), Mr. 

 C. T. Druery describes the phenomenon of Apospory in a variety of 

 the hart's tongue (Scolopendrium vulgare), a species in which it has not 

 hitherto been noticed. The variety (var. crispum Drummonda) has very 

 long, narrow fronds which are, moreover, finely frilled. In the plant 

 in question the tips of the fimbriate projections presented in many- 

 cases certain features characteristic of the vegetative production of 

 a prothallus, and when cut off with a portion of the fronds and 

 cultivated, distinct prothalli were produced bearing sexual organs. 

 This constitutes the fourth British species in which apospory has- 

 been observed. 



The Histology of Fossil Plants. 



In a recent communication to the Royal Society by Williamson 

 and Scott, an abstract of which has been sent us, we have an 

 interesting example of the steady progress of palaeobotanicaL 

 histology. 



A few years ago the " true fructification " of the well-known 

 Carboniferous Calamites was fully described by Williamson, and, in 

 1885, Renault expressed the opinion that the root of this genus was- 

 to be found in Astroinyelus. Renault's opinion has now been verified 

 in the case of English specimens of Astromyelus, and thus another step is 

 made towards a thorough knowledge of the morphology of Calamites^ 



