FERN GROWING 135 



ADDITIONAL EXPERIMENT NO. XLVIII. 



On October 12, 1894, a pan (marked A) was planted with 

 prothalli of a Scolopendrium, and on November 12 a second 

 (marked B) ; the plants are a quarter of an inch apart, and are 

 carefully protected from insects. On the 25th of January no 

 fronds had been formed, but the prothalli in A were much 

 larger than those in B. On that day several skipjacks were 

 introduced into B. On February nth every prothallus in B 

 had formed fronds, whilst those in A were still in the pro- 

 thalloid condition. In both pans the prothalli would have male 

 and female organs, as they were undivided ; nevertheless the 

 skipjacks have accelerated the formation of fronds. 



DEDUCTIONS AND PRACTICAL HINTS. 



Granting that the certainty of multiple parentage is difficult 

 of microscopic proof, owing to the practical impossibility of 

 seeing through the microscope what really occurs, this absence 

 of actual observation is far from justifying a refusal to accept 

 conclusions otherwise abundantly established by experiments 

 which show that the offspring bear unmistakable resemblance 

 to all the parents. 



Independently of the microscope, what are the reasonable con- 

 clusions established by these numerous experiments ? Briefly : — 



1st. — That more than one female cell on a Fern pro- 

 thallus is capable of producing Ferns. 



2nd. — That more than one spermatozoon has assisted in 

 the impregnation of one or more af these cells. 



3rd. — That a prothallus can be divided into four, and 

 each portion can produce a separate plant. 



4th. — That in quartering a prothallus there is evidence 

 that the organs of only one sex are retained on each of these 

 quarters. 



