280 TKANSACTIO]S*S AND PEOCEEDINGS OF THE [Sess. Lix. 



of those cases where the aposporous developments originate 

 from the sporangia, the archesporial cells — which would 

 give rise normally to the spore-mother-cells — do not take 

 part in the development, but become abortive (Linn. Trans., 

 vol. ii. plate 57). Accurate observations have not as yet 

 been made on either of these peculiar developments with a 

 view to ascertaining their nuclear condition, — it is there- 

 fore somewhat premature to discuss them ; but, putting 

 aside apogamy for the moment", I wish to offer a few 

 remarks on the phenomenon of apospory. In writing on 

 the subject some years ago (1887) I concluded that "the 

 phenomenon of apospory is a sport, and not a reversion 

 bearing pregnant interpretations with it" (Linn. Trans., 

 vol. ii. p. 323). This conclusion was thus stated in order 

 to meet and oppose the suggestion of Pringsheim, that the 

 phenomena of apogamy and apospory showed that the two 

 generations were not fundamentally distinct by descent. 

 Now their difference by history of descent is beginning to 

 be more clearly recognised, and the main points have been 

 stated by Professor Strasburger in very similar terms to 

 those in my own paper in the " Annals of Botany," August 

 1890. It is still true that apospory is not a reversion, in 

 the sense that the sporophyte thereby does not revert to 

 the primitive gametophyte. But in another sense it may 

 probably be regarded as a phenomenon of reversion : in 

 the primitive sporophyte, before vegetative development 

 of the tissues, all the cells were probably spore-mother-cells, 

 and capable of reduction of chromosomes. That faculty 

 was lost by certain cells as the vegetative tissues (sterile 

 or somatic ceUs) made their appearance, and thus the 

 reduction was deferred. It need, however, be no matter for 

 great wonder that, if this were the history, the cells which 

 normally do not exercise that faculty should on occasions 

 resume it : — that the unreduced somatic nuclei should on 

 occasions resume the faculty of reduction of chromosomes. 

 One point in the observed facts of aposporous develop- 

 ment is interesting and significant, viz. that when the 

 direct transition takes place from sporophyte to gameto- 

 phyte, the new development commonly springs, not from 

 one point only, but from many points, and, not from a 

 single cell, but from a number of cells. In such cases 



