+ 
422 BOTANICAL GAZETTE [ DECEMBER 
is everywhere the same, and that it is a typically closed hoop. Their present 
claim is that the closed hoop structure is unusual. They make the statement 
that “with some very important exceptions, the girdle is a two-ended band 
of silica, with the ends variously and characteristically rounded or otherwise 
modified, and approximated or overlapping without being joined. The posi- 
tion of the gap or joint is, within limits, constant in a given genus with rela- 
tion to salient features of the valves. In case of each simple pair of primary 
girdles, the two gaps are usually at opposite points of the diatom; and in 
general, in the forms we have studied, the gaps are normally so situated with 
respect to each other as to ‘lap joints.’’’ These claims are supported by the 
presentation of typical examples.—J. M. C. 
NOTES FOR STUDENTS. 
THE EFFECT of certain inorganic salts in accelerating the growth of lower 
plant organisms has recently been made the subject of research by N. Ono.” 
He has worked with the following substances in very dilute solutions: 
ZnSO,, FeSO,, NiSO,, CoSO,, CuSO,, HgCl,, LiNO;, NaF, and K,As0O3. 
For fungi Aspergillus niger and Penicillium glaucum served as subjects; 
for alge (and this is the first time this group has been brought under 
experimentation in this regard), Protococcus sp., Chroococcum sp., Hormidium 
nitens, and Stigeoclonium sp. Suitable nutrient fluids were used unmodified 
for the control cultures, and with addition of one of the above-named salts 
for the tests. | 
With the exception of CuSO, and HgClg, all of the salts, in very dilute 
solution, act upon the algze to accelerate vegetative growth and to retard the 
process of zoospore production. All of the salts act in this way upon the 
fungi studied ; in this the author is in accord with Richards.” For the alge 
the optimum growth is obtained by addition of a much smaller amount 
of the unusual salt than for the fungi. In the former case the concentra- 
tion of this compound varies from gram molecule per 
I 
128 inmmeae cytes 
100,000 
I 
2,500,000 
liter ; in the latter from —— to —— gram molecules per liter. Sixteen pages 
4000 800 
of tables give the results very clearly. The author has been content to deter- 
mine the facts as stated above, without inquiring more deeply into weak 
nature. He seems to make the mistake of considering his salts as remaining 
intact in these dilute solutions, instead of being completely dissociated, as 
they almost certainly are. It is very probable that (excepting in case © 
™ Ueber die Wachstumsbeschleunigung einiger Algen und Pilze durch chemische 
Reize. Jour. Coll. Sci. Imp. Univ. Tokyé. 13: 141-186. p/. 17. 1900. 
* Die Beeinflussung des Wachsthums einiger Pilze durch chemische Reize- 
Pringsh. Jahrb. f. wiss. Bot. 30:665. 1807. 
