T915] CURRENT LITERATURE 333 
Modification of germ plasm.—In connection with the twenty-fifth anni- 
versary celebration of the Missouri Botanical Garden, MacpouGat* has pub- 
lished an account of the work done at the Desert Laboratory of the Carnegie 
Institute in experimental modification of germ plasm. It is directed against 
the old conception of “an inviolable germ plasm,” in the interest of the con- 
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At the Desert Laboratory over 200 species of seed plants, selected for their 
suitability and promise of response, have been included in the ete ene 
jected to various conditions (mountain top, desert, and seashore). 
80 of these have survived, and about 20 continued in all three lems ‘The 
notable feature in the behavior of these plants in ear habitats is 
oo variation in sexual echevaiceesennet and seed formation. A secon od 
sci ted bodies. In this kind of experimental work the forms chiefl 
used at the Desert Laboratory were certain cacti, Penstemon Wrightii, and 
an undescribed species of Scrophularia, the results reported in the paper being 
chiefly obtained from the last form. The paper concludes with a condensed 
statement of the conditions involved in any experimental work upon the germ 
lasm.—J. M. C 
Bacterial diseases of plants.—SMITH,” in a paper presented at the twenty- 
fifth anniversary celebration of the Missouri Botanical Garden, has summar- 
ized our present knowledge in reference to the bacterial diseases of plants, all 
of which has come within a generation. It is an interesting historical fact 
that our first knowledge of such diseases was the announcement by BURRILL 
in 1878 that. pear blight is a bacterial disease. Smiru states that he is now 
ready to venture the sweeping statement that eventually a bacterial disease 
‘will be found in every family of plants, from the lowest to the highest. At 
present such diseases are known to occur in 140 genera, representing more than 
50 families. The paper includes a list of the families of seed plants, those i in 
appearance of the disease; recovery from disease; agents of transmission; 
extra-vegetal habitat of the parasites; action of the parasites on the host; the 
reaction of the host; prevalence and geographic distribution; and methods 
of control.—J. M. C 
. Stem anatomy of Isoetes.—LANG has begun an investigation of Isoetes, 
whose problems, as he remarks, remain difficult and fascinating. The first 
2 MacpoucaL, D. T., The experimental modification of germ plasm. Annals 
Mo. Bot. Gard. 2:253-274. figs. 4. 1915. 
2 SmirH, Erwin F., A conspectus of bacterial diseases of plants. Annals Mo. 
Bot. Gard. 2:377-401. 1915. 
