206 
POPTJLAK SCIENCE REYIEW. 
evolve carbonic acid, or some other oxidized substance, as an essential condition 
of the evolution of their structures'’’ 
The “ Yucca ” and the Pronuba." — According to the researches of 
Professor Piley, which will he published in the Transactions of the St. 
Louis Academy of Sciences,” these two — plant and animal — are wonderfully 
interdependent. He lately described the generic and specific characters of 
a little moth, which is one of the most anomalous known to entomologists. 
He first described how many of our flowers, such as the Ascelpias and 
Orchids, were curiously constructed so as to be incapable of fertilising 
themselves, and at the same time to attract insects to do it for them. Dr. 
Englemann had this year discovered that Yucca was one of those plants 
which depended on insects for fructification, and Professor Piley had dis- 
covered that the little moth in question, which he calls Pronuba guccassella, 
is the only insect which can have anything to do with this fructification. 
But what is more interesting in this ease is, that the plant not only depends 
on the assistance of the moth, but that the moth, in turn, is likewise depen- 
dent upon the plant, since its larvse live on the seeds. We have, con- 
sequently, a mutual interdependence which is very striking, and in the 
structure of a female moth there is a curious adaptation of means to an end 
by a complete modification of parts, and especially of the maxillary palpi, 
which are formed into prehensile tentacles, by which she collects the pollen 
to insert it into the stigmatic tube. 
Origin of Weeping Willows. — In a late number of “ Silliman’s American 
Journal,” a writer, whom we imagine to be Professor Gray, says that from 
the investigations of Karl Koch it appears that the Garabf upon which 
according to the Psalmist, the captive Jews at Babylon hung their harps, 
is not the weeping willow named Salix Bobylonica by Linnaeus in view of 
the current tradition, and is not a willow at all, but a poplar. Indeed 
Panwolf had long ago concluded that it was not a willow. And the Salix 
Babylonica, the hardiness of which attests a cooler climate than that of 
Mesopotomia, is now regarded as of Chinese or Japanese origin ] so that its 
Linnaean specific name gives place to that of Salix pendula Moench. 
Dicranum undulatum in Britain. — Dr. Pobert Braithwaite, writing to the 
first number of Grevillea ” for the present year, says: — This may now with 
certainty be entered as a member of our Moss-Flora, Prof. Lindberg having 
detected it in Mr. Spruce’s herbarium. Having recently paid a visit to that 
gentleman, he kindly gave me some of his original specimens, and informed 
me that he found it in August, 1842, growing in dryish sand-pits in a fir 
plantation on Stockton Forest, near York, and although specimens were sent 
to the late Mr. Wilson, it has no place in his ‘ Bryologia Britannica.’ My 
friend Mr. Anderson of Whitby, has found it again in the same locality a 
few weeks ago, and it is probable that it occurs in many other places ; but, 
being barren, has not been distinguished from D. scoparium or D. Bonjeanii; 
at least this is much more probable than that such a widely diflPiised Conti- 
nental and American species should be totally absent from Britain. Mr. 
Spruce informs me that it is not uncommon in the lower Pyrenees, growing 
in grassy glades of sandy woods.” 
The Selective Power of Plants. — Prof. S. W. Johnson, of Yale College, 
Connecticut, has called our attention to the circumstance that in the 
