FERN GROWING 125 



Altogether these experiments have been remarkably suc- 

 cessful, for the different varieties raised were obtained in the 

 identical manner formulated before they had an existence. 

 The anxiety, labour, and attention have been great, and the 

 time occupied has been half a lifetime, but in the success 

 gained there has been ample reward. 



On October 15, 1893, on^ of the two remaining portions 

 of the split prothalli that had been more than six years without 

 putting on frond life at length threw up a frondlet. How 

 this has happened it is impossible to say ; there was not 

 another prothallus within several feet of it, and moreover it 

 has always been under a sheet of glass. It can only be 

 conjectured that sperms have by some means been conveyed 

 from a distance (probably clinging to an insect, for a small 

 insect, Podura plumbea or skipjack,* was noticed, which might 

 have been there for some time, as the plant had not been 

 examined for three weeks owing to the author's illness). 

 In the hundred examples of split prothalli such impregna- 

 tion had never before occurred. The prothallus is as healthy 

 now as ever, showing no signs of that decay which is apparent 

 when frondlets form. In its present infantile condition it is not 

 possible to say further than that, like the mother-cell, this is 

 a Scolopendrium. There is, however, in this new fact, proof 

 against those generally conceived views as regards how im- 

 pregnation of the prothallus takes place. It may be some 

 other method of growth, though the author attributes it to 



* It is not only an important fact that the Skipjack can convey sperms from the 

 antheridia to the archegonia, and by this means the oosphere becomes fertilised, but 

 by placing a skipjack amongst prothalli having only archegonia, i.e., female cells, 

 and allowing it to remain there for only twenty-four hours, we are able to ascertain 

 within a few hours when impregnation must have taken place, and by afterwards 

 watching for the appearance of frondlets we can further know the period required 

 between impregnation and the development of fronds. In this instance frondlets 

 were seen on the fourteenth day, but they were certainly two or three days old when 

 detected, therefore this period is probably twelve days. 



