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least dainty in its requirements, seeming to have no antipathy in 

 the matter of soil or position, and in many localities thriving in 

 abundance under the most adverse conditions." Mr. Druery is 

 inclined to the belief that this paucity in certain sections is due to 

 the "greater or less predominance of certain forms of minute insect 

 life. * * Just as we find in our gardens that certain vermin 

 attack and destroy certain plants, so it is only reasonable to as- 

 sume that either the spores or prothalli of these ferns are the favo- 

 rite food of some of the minuter insects, in order to explain the 

 absence of adult plants. Climatal conditions are, of course, a 

 potent factor, but do not account for all the phenomena observed." 

 Mr. Druery then cites the cases of certain exotic ferns which attract 

 slugs or snails, and must be grown in isolation. Such a one is 

 Cainptosorus, in England. "Other plants," he writes, "are espe- 

 cially subject to the attack of wood lice ; and so, doubtless, such 

 special appetites characterize also the minuter and microscopic 

 insect world, and as it is manifest, when we consider the myriads 

 of spores which are shed in vain, that these must become mainly 

 the food of such tiny creatures, we need hardly seek further for a 

 solution of the mystery. A harder or softer envelope to the spore, 

 or a more or less attractive flavor in this plant itself, would deter- 

 mine for or against its survival in the struggle for existence." 



It seems necessary to suppose that some such cause operates to 

 effect the odd distribution both in England and America. In 

 March, 1898, I noticed the presence of one of the Lace bugs 

 (Tingitidae), upon plants at Jamesville, in considerable numbers. 

 They seemed mostly to attack the spores, but were found appar- 

 ently destroying the leaves as well. Snails are often found depend- 

 ing from badly eaten fronds. These scant observations tend to 

 substantiate Mr. Druery' s proposition. It is indeed perfectly sup- 

 posable that in certain of its various stages of development, it may 

 peculiarly attract vermin to itself, which so greatly impair its 

 vitality as to lessen its chances for survival and reproduction. A 

 series of careful observations and experiments along this line would 

 be of the greatest interest. 



U. S. National Museum, \Yashington, D. C. 



