1901] CURRENT LITERATURE 151 
of the Conjugatae, while the desmids and diatoms are believed to represent 
two similar and somewhat parallel genetic lines in which the filaments tend 
to break up rather early into independent cells. The larger part of the 
paper is occupied by a key to the tribes and genera of the American forms.— 
CHARLES J. CHAMBERLAIN. 
NOTES FOR STUDENTS: 
EXPERIMENTS by D. Neljubow* have shown that the peculiar horizontal 
nutation of stems of seedling peas (Pisum sativum) grown in darkness at high 
temperature is due to the presence of small amounts of illuminating gas in 
the air of the laboratory. It is especially the acetylene and ethylene com- 
ponents of illuminating gas which are active. SO;, and vapors of CS, 
xylol, and benzol are very injurious. This peculiar reaction to gas seems to 
have been unknown before.— C. R. B. 
A FEw interesting points epsceaias the behavior of apples in cold storage 
are brought out in a bulletin’ by L. C. Corbett on this subject. ith the 
exception of York Imperial, the apples of all varieties tested lost less in weight 
when stored in the light than when kept in darkness. The acid content of 
was decreased in some varieties and increased in others. No explanation for 
these differences of behavior is attempted.— Ernst A. BESSEY. 
A NUMBER of experiments throwing light on the method of infection in 
pear blight are described in a bulletin® from the Delaware Experiment Sta- 
tion. The germs were introduced by means of needle punctures into termi- 
nal shoots, one year old wood, three year old wood, buds, leaves, and fruit. 
Leaves and young twigs were smeared with cultures of the germ and kept 
moist fora time. The latter, however did not cause the disease to develop, 
for it appeared only where the germs had actually been introduced into the 
tissue, as for example, where needle punctures had been made into the pres- 
ent year’s terminal shoots, into buds, leaves, and into the fruit. The 
pointed out by Waite, by transference of the germs by honey-seeking insects 
from nectary to nectary, and into the fruits, young succulent shoots, and 
leaves by the introduction through bites and punctures of insects of germs 
clinging to their mouth parts. The same bulletin reports the occurrence in 
Delaware of pear canker, which seems to be caused by Sphaeropsis malorum. 
4 Beihefte z. Bot. Cent. 10: 128-138. figs. 2. 1901. 
_5CorsBett, L. C.: Cold storage. Bull. West Virginia Agr. Expt. Sta.) 74: 
51-80. figs. 3. March 1901. Morgantown. 
6CuEsTeER, F. D.: Pear blight and pear canker. Bull. Delaware Agr. Expt. 
Sta. 52: 1-8. figs. 1-7. April 1901. Newark. 
