Nov. 1894.] BOTANICAL SOCIETY OF EDINBURGH. 281 



it would appear that reduction had taken place in a con- 

 siderable number of cells. This would seem to indicate 

 that the change of condition is a somewhat general one 

 for the parts involved, depending probably upon some 

 peculiarity of general physiological condition of the plant 

 or part in question. What that physiological condition is, 

 and how produced, it is difficult to suggest. In the case 

 of the mosses in which apospory was induced by Pringslieim 

 and by Stahl, moist culture was successfully adopted. 

 This certainly assists the developments in ferns when once 

 initiated, but I have found that attempts to induce 

 apospory in ferns by moist culture of small portions of the 

 fronds was entirely without success, though a large number 

 of species were tried (Annals of Botany, vol. iv, p. 168). 

 The conclusion was thus arrived at, that the phenomenon 

 of apospory is by no means a promiscuous one, occurring 

 readily and often, but a process which seems to appear 

 spontaneously under conditions not yet understood, and is 

 not readily induced. It may now be added that there is 

 probably an internal initiative leading to the reduction, 

 while conditions of moist culture are favourable to, though 

 probably not the prime cause of, the subsequent prothalloid 

 growths. 



While the phenomenon of apospory may thus be looked 

 upon as in a sense a phenomenon of reversion, — cells nor- 

 mally somatic having resumed their pristine faculty of 

 reduction of chromosomes, it is more difficult to suggest 

 any explanation of the apogamous condition ; and, in either 

 case, we must wait for observation of the nuclear details to 

 lead with any degree of certainty to the true interpretation 

 of these interesting abnormalities. 



Turning now to the third point, viz, the theory of the 

 process of reduction : As above noted, Strasburger concludes 

 that the individuality of the chromosomes is maintained, 

 even though their identity cannot be microscopically 

 observed in the resting nucleus. No extrusion of chromo- 

 somes, or absorption of them, has been seen in cells of plants 

 which could account for the reduction ; it is believed that 

 the reduction is due in each case to the fusion of two 

 chromosomes into one. Further, each chromosome is 

 recognised as being composed of alternating discs of 



