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how moist conditions are essential to successful spore 

 propagation, especially at the critical period when fertiliza- 

 tion should occur. This is the normal life cycle of all 

 Ferns, but, thanks to careful study of the varietal forms, it 

 has been found that Nature has not only endowed Ferns 

 with a capacity to sport as far as outward appearance and 

 structure go, but that every conceivable variation of this 

 life cycle occurs. Normally, the succession is Fern, spore, 

 antheridia, archegonia, embryo seed and Fern again ; but it 

 has been proved that reproduction can take place, leaving 

 out every one of these stages either singly or even in the 

 lump, including the apparent paradox, the very Fern itself. 

 In the variant known as Apospory, the fern cuts out the 

 spore by forming the green scale direct.on its fronds, in that 

 known as Apogamy the embryo seed and its adjuncts are 

 omitted, the young fern appearing as a bud on the scale. 

 In such ferns as are bulbiferous, bearing young plants on 

 the fronds, the scale and all intermediate stages are, of 

 course, left out, while the final apparent paradox is solved 

 by the fact observed by Dr. Lang that the scale itself was 

 capable of producing spores direct, and, of course, if these 

 spores inherited that capacity, the Fern as we know it 

 would be omitted altogether, and only generation after 

 generation of the scale stage would exist. It will be seen 

 from these data that the cross fertilization of Ferns cannot 

 be conducted on the same sure and scientific lines as that 

 of flowers. With flowers we can take precaution against 

 self fertilization, and we can easily transfer what pollen we 

 will from one flower to a different one and be fairly certain 

 what pairs are united. With ferns, on the other hand, in 

 which self fertilization must be the rule and crossing a rare 

 accident, we cannot possibly either handle the pollen 

 equivalents or be sure that fertilization has not already 

 occurred. All we can do is to sow the two kinds of spores 

 together somewhat closely, or bring pairs of young prothalli 

 from dift'erent sowings into close juxtaposition before 

 maturity, flooding them then from time to time on the 

 chance that the roving antherozoids may thus be carried 



