800 ‘The American Naturalist. [September, 
mit welchem der Blattrand den Stiel berührt, und streckt sich 
mehr vor als die übrigen Zähne des Blattgrundes. An den 
inneren Rändern dieses Zahnes entsteht mit der weiteren Entwick- 
elung ein zweiter Zahn, und beide erscheinen schon als kleine 
selbständige Lappen; wenn nun deren Grösse so lange wächst, 
bis diese zwei kleinen Seitenläppchen an einem Punkte sich 
berühren, so beginnt das Wachstum von diesem Punkte aus nach 
unten, und dieser Teil der Lamina ist nicht mehr an den Stiel 
gewachsen, sondern sondert sich von ihm ab. Dieses Läppchen 
ist manchmal ziemlich gross und kann im Allgemeinen als Resultat 
einer progressiven Entwickelung betrachtet werden.” 
I have never found it in that species as introduced into our 
American parks, where care is taken to trim out the sprouts and low 
branches on which it would occur, if atall. Fig. I represents a 
typical leaf of that species. But in the American form P. oceiden- 
talis in its wild state, especially on those abundantly nourished 
shoots of the season that spring from the base of stumps where 
the trees have been felled, I have for years observed it in all its 
phases, and studied its many curious transitions. These I have 
described, and have figured some of them in the papers men- 
tioned, to which I would respectfully refer the reader. 
In the original paper which I read before the Biological Society 
of Washington on February 20, 1886, I exhibited some forms 
that better illustrate the phenomenon than any that have been 
published. One of these I had figured, and sent the drawing, 
together with others and the paper itself, t0 one of the editors of, 
the American NATURALIST, at his request, for publication in that 
journal; but unfortunately it did not appear, owing to a change 
that took place in the publishers of the NaruraLıst just at that 
time, in the course of which my manuscript was mislaid and 
could not be found. It has recently come to light and been 
returned to me,and I am able to introduce here (Fig. 2) the 
figure in question. 
In view of the importance of the basilar expansions above men- 
tioned, and of the fact that Professor Jankó excludes such forms 
as P. nobilis from the genus Platanus, I may perhaps be permitted, 
at the risk of some repetition of what has been said in my previous 
