THE PSILOTALES 



where it was merely kept in water for a spell of some weeks, was still in meiosis at the end 

 of the time but showed perfectly normal spindles. This confirms the suggestion made in 

 relation to Rangitoto that the meiotic irregularities found there are metabolic in origin. 

 Tetraploid sporophytes are thus now known from New Zealand and Australia; they 

 may be suspected to be present in parts of Japan from the work of Okabe (1929), and 

 a rhizome count reported from Malay (Manton, 1942) was also of this nature. The only 

 certain diploid sporophyte so far referable to an exact locality is one from Ceylon 

 (Manton, 1942). It is obvious, however, that very large tracts of the earth's surface are 

 entirely unexplored, and it is still too soon to know whether the diploid or the tetraploid 

 sporophytes will have the wider distribution. 



Fig. 235. Meiosis in tetraploid Psilotum nudum (L.) Beauv. (P. triquetrum Swartz) from Kew, permanent 

 acetocarmine. x 1000. From the specimen of Fig. 229, after Manton (1942). 



From what has been said it will be obvious that in Psilotum the fact of polyploidy is of 

 far greater interest than the actual details of the chromosome numbers, and for this 

 reason it has been discussed first. It now remains to add the numerical details as far as 

 these are known, which, unfortunately, is still only imperfectly. My own information is 

 still exactly as in 1942. The only diploid sporophyte available to me alive was a plant 

 of P.Jlaccidum, of unknown wild origin, growing at Kew (Fig. 230, p. 235). In this there 

 are not less than 52, nor more than 54, chromosome pairs at meiosis (Figs. 236 a, 237), 

 though I was unable to decide between these two numbers. This is the only record of 

 P. flaccidum so far available, but in the best modern study of P. nudum {P. triquetrum) 

 known to me (Okabe, 1929) the haploid number for horticultural strains in Japan is 

 given as 52. This number is therefore undoubtedly very near to the truth. Fig. 235 

 shows meiosis in a tetraploid sporophyte, also of unknown wild origin, growing at Kew in 



239 



