1 90 THE BEGINNINGS OF LIFE. 



cell.' I have also, of late, since having become ac- 

 quainted with these observations of Mr. Carter, re- 

 peatedly watched the formation of independent cells 

 of this kind within the filaments of Vaucheria resulting 

 from modifications taking place in what were at first 

 irregular masses of protoplasm containing chlorophyll 

 granules. A definite cell-wall is soon formed around 

 these variously-sized masses, whilst the most striking 

 changes also take place in the substance of the newly 

 constituted cell. These changes, however, will be more 

 fully described in a later chapter. 



Hitherto we have been speaking of Cryptogamic 

 plants, but through the admirable researches of Hof- 

 meister l we know that just as good instances of ' free ' 

 cell formation are to be met with amongst the Pha- 

 nerogamia, or o dinary flowering plants. The inves- 

 tigation of the subject here, is however much more 

 difficult for the observer. There is this difference also, 

 with these more complicated plants, that the embryo-sac, 

 or mother-cell, itself persists for a time, instead of being 

 destroyed by the reproductive process, We will quote 

 the description given by Braun 2 of the phenomena 

 taking place during the formation of the seed in one 

 of the flowering plants. He says : c The embryo-sac, 

 or germ-sac, as it is termed, is the last cell of the 

 mother plant, the uppermost in the axial row of cells 

 of the ovule, destined to become the focus of re- 



1 ' Der Enstehung des Embryos der Phanerogamen,' 1849. 

 2 Loc. cit. p. 276. 



