females actually observed. This only applies of course to sporogonial localities where no other stages were actually recorded. FEMALE MALE SPOROGONIAL No. of No. of No. of No. of No. of No. of Localities V.C's Localities V.C's Localities V.C's Records England 652297 Actually Observed Wales &11 3 4 3 1 1 [Mon. Assumed f England 9 5 8 6 Records Wales & o o lMon. Totals 26 13 14 11 10 8 It is clear from the table that female plants have been observed more often than sporogonial plants in Wales, whereas the reverse is true in England. It is most likely that whilst in reality, females are far commoner than the spore-bearing stage in both regions, the former, being less conspicuous, have previously escaped attention in England. This is borne out by the comparatively large number of Assumed Records for female plants in England. The great rarity of male-plants immediately raises the follow- ing questions (a) Are male plants truly rarer than female plants ? (b) Are male and female plants equally common, the males being less conspicuous, having been overlooked ? Judging by the number of Assumed Records for male plants it is clear that whilst males are far commoner than the actual records suggest, it is still of course possible that the sexes are not equally frequent. It may be that potentially male (but sterile) plants, although present in equal numbers with potentially female (sterile) plants, produce sex-organs less readily, or perhaps males are less viable than females. It was found however that both male and female plants when living in cold frames appeared to have grown equally vigorously and produced sex-organs equally pro- lifically, in some instances for three years in succession. This fact tends to suggest that neither of the above explanations is com- pletely adequate in accounting for the number of male and female plants. Yet another likelihood is that Lunularia may have been intro- duced into the British Isles chiefly by female plants. It is necessary of course to obtain many more records of sexual and spore-bearing plants in order to test this hypothesis. Another feature of interest is that although both male and female plants have occasionally been recorded fairly near one another, fertilisation may not occur. An obvious explanation is that sperms are often not able to complete the journey to the female organs. An alternative suggestion is that some males are rendered incompatible to certain females by their hereditary organisation