950 



not always been as yet inquired ; and even where this has been done, 

 it still remains doubtful, and frequently requires accurate anatomical 

 investigation, which cannot be instituted by the descriptive botanist, 

 or one who applies description to the recognition of species. On 

 these principles the expression ' involucrum ' for Setaria may be rea- 

 dily justified, and the addition 'setosum' likewise, for the fibres 

 themselves are stiff and bristly. What is a seta, is very differently 

 defined by botanists, and the describer can only have regard to the 

 filamentous form, and stiffness of the bristle of an animal. Cynosu- 

 rus has no involucrum, as I have also stated in * Hort. Bot. Berol.' — 

 ' spiculae fultae bracteis pinnatifidis ;' for these parts represent bracts, 

 though they might also be glumes grown together." 



New Theory of the Fertilization of Plants. — Dr. Hartig has here 

 presented some valuable observations on a most interesting subject, 

 which has more than once been ably treated on by Mr. Wilson in the 

 pages of the ' Phytologist.' After some remarks on the present state 

 of the doctrines with regard to Fertilization, the author " proceeds in 

 the first section to endogenic impregnation, or to impregnation in the 

 interior of the ovary. In this case, for instance, a pollen-tube, or 

 tube of pollen-grain (Ballschlauch), as the author says, reaches as far 

 as the ovum, penetrates into the foramen of the ovule, grows through 

 the cellular tissue of the nucleus (Befruchtungskegel) to the spot 

 where the germ originates. According to the author, in the Coniferae 

 the pollen itself enters the micropyle of the naked ovum, attaches it- 

 self firmly to the ovule (Befruchtungsei), and sends a short tube into 

 the cellular tissue, in consequence of which a series of remarkable 

 formations commences, the last of which, after an interval of more 

 than a year, in those Coniferae that are two years in maturing the 

 seeds is the commencing germ, as was previously quoted from the 

 author's ' Lehrbuch,' in the former yearly Report. The pene- 

 tration of the tube into the ovule has been satisfactorily ascertained 

 in many families ; but it is the object of the author to show, that fer- 

 tilization does not always take place in this manner. This is followed 

 by the impregnation of the placenta. In a number of plants by no 

 means insignificant, the pollen-tubes can be traced as far as the 

 ovary, sometimes even to its base ; while we seek for them in vain in 

 the foramen of the ovum, as in many CEnotherae. In all plants, con- 

 tinues the author, to which a deeper introduction of the tube is gene- 

 rally peculiar, the tube turns itself in the shortest way to the cellular 

 tissue of the stigma, penetrates the cuticle, the superficial and the 

 cortical cells, to the central bundle of vessels, and runs from thence 



