42 Wisconsin Academy of Sciences, Arts, and Letters. 
Similar facts are also reported by Waldron 82 from North 
Dakota. While from Porto Rico 83 we learn that the northeast 
wind prevailing there causes citrus trees to grow slowly and 
one-sided in unprotected places; the bark looks dead and the 
new shoots are variously twisted. A case is cited where two 
similarly planted citrus groves are located across the road from 
each other but one is protected by a windbreak while the other 
is fully exposed. The trees had all been set three years and 
were bearing in the protected grove while in the exposed one 
they looked as though they “had just been set.” Wind-exposed 
trees were also found heavily infested by scale-insects while the 
protected ones were practically free from the pest. 
In a very recent paper 84 it is stated that the wind induces 
dwarfing and the rosette habit, although the structural modifi¬ 
cations are attributed to excessive transpiration. 
A like conclusion was recently also drawn by Choux. 85 He 
found that the stems of Neptunia prostrata and of Ipomea rep- 
tans grown during the tropical dry season were not only smaller 
but that their vascular systems were much more strongly devel¬ 
oped than in those produced during the wet season. Starch was 
abundant in the dry season plants and practically absent from 
those grown in the wet season. 
The hypothesis advanced by Schwendener and subsequently 
elaborated by Metzger and Schwarz and the more recent one by 
Jaccard are so simple and imbued with such insidious directness 
that they are fascinating although not wholly convincing. Af¬ 
ter making a brief survey of the observations and experiments 
by Jost, Lutz, Fabricius, Rubner, etc., it seems as though the 
occurrence and distribution of radial growth could not be de¬ 
pendent on a single factor. It appears for instance that the 
distribution of elaborated food must in part at least depend upon 
its place of manufacture and on the channels of its transport, 
especially when the amount available is somewhat below the 
sa Waldron, C. B. Windbreaks and hedges. N. Dk. Agrl. Expt. Sta. 
Bui. 88. 1910. pp. 11. 
ss Tower, W. Y. Insects injurious to citrus fruits and methods for 
combating them. Porto Rico Agrl. Expt. Sta. Bui. 10:16-20; 35. 1911. 
84 Kroll, G. H. Wind und Pflanzenwelt. Beihefte Bot. Centralbl. 
30 Abt. 1:122-40. 1913. 
85 Choux, P. De Pinfluence de l’humidite et de la secheresse sur la 
structure anatomique de deux plantes tropicales. Rev. Gen. Bot. 25: 
153-72. 1913. 
