98 FERN GROWING 



seedlings there are a number that have converted this cup 

 into a thick muricate one, of more than an inch in length ; 

 and in others the murications across the surface of the fronds 

 are minutely cupped, whilst others have in addition a mar- 

 ginal ridge. In some, instead of a cup, there is a rugose 

 rosette. 



It is thought desirable to defer illustration, as this may 

 eventually add another link in the chain as regards multiple 

 parentage. 



Roughly it may be said that when six varieties are sown 

 together, one plant in a thousand will show all the six 

 characters ; with four varieties, about one in two hundred ; 

 with three, one in fifty ; whilst with two, not less than- nine 

 hundred and fifty in a thousand. 



EXPERIMENT NO. XVI. 



In 1889 spores of the Asplenium Ceterach were sown 

 with those of the Ceterach aureum of Madeira, a representative 

 of our English Ceterach on a gigantic scale ; these are now 

 of mature size, having much larger fronds than the English 

 species, yet much smaller than those of the Madeira form. 



The author has said that hybrids are all but sterile, 

 and as these seedlings yield young plants as freely as the 

 ordinary Asplenium Ceterach, we are prepared to assert that 

 the two are forms of the same species.* 



As a caution to those who feel an inclination to repeat 

 any of these experiments, the author adds that the spores 

 must all germinate, or, rather, the prothalli must arrive at 

 maturity at the same time, or a cross will not be obtained. 



Spores sown after being kept months or years take a 

 far longer time to germinate ; it is therefore obvious that 



* For illustrations refer to Asplenium Ceterach var. Kalon, page 104. 



