684 MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 



CHAPTER XI 



OF THE MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 



BETWEEN the two great divisions of the Vegetable Kingdom which 

 are known ; is Cryptogamia and Phanerogamia the separation is by 

 no means so abrupt as it formerly seemed to be. For, as has been 

 already shown, though the Cryptogamia were formerly regarded as 

 altogether non-sexual, a true generative process, requiring the 

 concurrence of male and female elements, is traceable almost through- 

 out the series. And in the higher types of that series we have seen 

 a foreshadowing of those provisions for the nurture of the fertilised 

 embryo which constitute the distinctive characters of the Phanero- 

 ganiia. On the other hand, although we are accustomed to speak of 

 Phanerogamia as ' flowering plants,' yet not only are the conspicuous 

 parts of the flower often wanting, but in the important group of 

 Gymnosperius (including the Conifercv and Cycadecd) the essential 

 parts of the generative apparatus are reduced to a condition closely 

 approximating to that of the higher Cryptogams. There are, how- 

 ever. certain, fundamental differences between the modes in which 

 the act of fertilisation is performed in the two groups. For (1) 

 whilst in all the higher Cryptogams it is in the condition of free- 

 nioviiig ' antherozoids ' that the contents of the sperm-cell find their 

 \\.-iv to the germ-cell, these are conveyed to it, throughout the 

 phanerogamic series, by an extension of the lining membrane of the 

 sperm-cell or pollen-grain into a tube, which penetrates to the germ - 

 cell, contained in the interior of the body called the ovule. 1 Again 

 (2), while the ' germ-cell ' or oiisphere in the higher Cryptogams is 

 contained in a structure that originated in a spore detached from the 

 parent plant, it is not only formed and fertilised in all Phanerogams 

 whilst still borne 011 the parent fabric, but continues for some time 

 t<> draw from it the nutriment it requires for its development into the 

 i iiiln-i/o. And at the time of its detachment from the parent the 



1 A ver\ remarkable and inteiv iting discovery, for which ue are largely i 

 to the brilliant observations of twn Japanese botanists, Professors Ikeno and Ilirasc, 

 lias recently thrown great light on I lie approximation referred to by Dr. Carpenter 

 between Uie higher Cryptogamia and the lower Phanerogamia. It is now known 

 that in both the larger groups of (i\ nmo, perms, tlie ('onifene and the Cycadeee, there 

 are species in \\liich the fertilising liod\ is a motile ant hero/.oid formed \\ithin a 

 pollen tube, thus romliining (he distinctive modes of fertilisation characteristic of 

 tin- two gi-eal sections oi the vegetable kingdom. As Dr. Carpenter does not include in 

 his account of the ' Microscopic Structure of I'li.-nierogainic 1 'hints ' a full description 

 of the modi! of impregnation in (lowering plant-, the reader is referred, for further 

 detail . to the mosl recent Text I ..... bs of Botany, or to the Summary of Current Re- 

 searches in liotany iii the funrinil i if flu- li. Mii-rt'^cujiiciil Society. EDITOR.] 



