378 The Botanical Gazette. [August, 
pollinated plants thus show an advantage over the cross-pollinated 
only under the pseudo-ecological conditions induced by the hand of 
man. This disposes of one of the objections of the apostles of self- 
pollination who have long been distinguished for a facility in mixing 
heterogeneous data. 
On the relation between the mode of pollen transfer and the struc- 
ture of fruits, the author calls attention to the fact that in wind-pollin- 
ated plants, in a great majority of cases, the fruit is one-seeded or few- 
seeded, while among entomophilous plants the fruit is commonly 
many-seeded. This is explained as owing to the fact that in the latter 
case the pollen is more readily carried in quantity sufficient to fertilize 
many ovules. Among the indigenous plants Populus and Juncus are 
the only anemophilous species which are polyspermous. The case of 
Juncus may be explained by the fact that many of the species can self- 
pollinate. That of Popudus may be accounted for on the hypothesis 
that the plants are descendants of entomophilous forms. I suspect 
that this hypothesis may be shown to be quite probable. Warming 
has observed that in the Arctic regions Sax shows a disposition to 
resort to anemophily, and this will support us in the supposition that 
Populus has gone through an entomophilous stage. To the indirect 
agency of insects, therefore, it seems that we must attribute the devel- 
opment of the great variety of polyspermous dehiscent fruits. The 
theory suggests that the union of many pollen grains in compact 
masses, as a favoring condition, may explain the development of a 
high degree of polyspermy in the orchids. 
MacLeod has produced an admirable work which well deserves be- 
ing cited by Willist as a model of this kind of investigation. CHARLES 
ROBERTSON. 
Minor Notices. 
ANOTHER VOLUME in the botanical series of Ostwald’s Classics* 1n- 
troduces the reader to Andrew Knight? and his writings. Six © 
Knight’s interesting articles from the Transactions of the Royal So- 
ciety, beginning with that most famous one of all which proved that 
roots and stems take their position in response to gravity, are given, 
followed by a brief sketch of his life, notes by the translator, and an 
enumeration of 93 titles of articles on plants published between 1795 
and 1838. Knight wrote in a very attractive way, and for many Tea 
Sons these essays are rightly considered classical. This neat little vol- 
ume merits a warm reception from the public. 
‘The Natural History of the Flower. Natural Science 4: 351. My 1894 
2 i . bers are reviewed in this journal, 19: 207. 
NIGHT, TH iologi . 
(803-1812) Usberscet und herausgegeben a Agee Goalie Riss 
siker ten Wissenschaften, Nr. 62. 12mo. pp. 63. Leipzig, Wilhelm 
