form has been found on plants that had not been injured and 

 were growing under normal conditions. 



There is an imperative law of nature which makes the per- 

 fection of fruit dependant on the perfection of foliage. We can- 

 not expect perfect fruit from a tree denuded of its leaves, yet we 

 know that a tree may have abundant foliage and yet produce im- 

 perfect fruit. So undoubtedly, the sterile fronds of Onoclea are 

 indispensible for the perfection of the fertile, and if the sterile 

 fronds are destroyed we may expect immature fertile fronds, but 

 there is no reason that I can see why we may not occasionally find 

 imperfect fertile fronds, and even transitional conditions on plants 

 where the sterile fronds have not been destroyed, and this I claim 

 has been done. 



In October, 1881, I published in the Torrey Club Bulletin 

 some observations of my own, to supplement those published by 

 Dr. Underwood in September. The facts stated by him I knew 

 by my own experience, to be true and his conclusions were justi- 

 fied by them. I have myself had similar experiences, and adopted 

 similar views; but subsequently different experiences caused me 

 to modify my views, and it was these later experiences that I pub- 

 lished, as it seemed to me that they suggested some different con- 

 clusions from those previously held by myself and adopted by 

 Dr. Underwood, and that it was important that they should be 

 published as a contribution toward supplying data for a proper 

 solution of the whole problem. 



As the facts which I then gave have never been controverted 

 or explained, they still remain important factors in any solution 

 that may be offered for explaining the causes which bring about 

 the production of the obtusilobata form. The more important of 

 the facts then stated, were: 1st. That while I had collected 

 specimens in open meadow lands, where its appearance subse- 

 quent to mowing time suggests a probable cause and effect, I had 

 also collected it plentifully in situations where no scythe had ven- 

 tured, and where the plants were otherwise perfectly developed 

 — the sterile fronds being well grown — and in some cases bear- 

 ing normally developed fertile fronds as well as the variations. 

 2d. That I had found one season, near a rivulet, and on a stony 

 patch left unmown at the edge of a meadow newly mown, some 

 of the finest obtusilobata I had ever collected, obtaining four 

 specimens from one plant alone. This plant I marked, and re- 

 visiting it the next season found that it had resumed its normal 



