~ 
1907] CURRENT LITERATURE 143 
ulated tips in about the quantity of 16 per cent., while in stimulated tips it is 
present to the extent of about 20 per cent. Such figures can be obtained with 
considerable accuracy by an improved application of the silver reduction test. 
increased quantity of homogentisinic acid. The oxidation of this acid is accom- 
plished in ordinary metabolism by an enzyme, which because of its activity with 
phenol is called phenolase. The normal activity of this enzyme prevents accum- 
ulation of homogentisinic acid above c. 16 per cent. In consequence of stimu- 
lation, however, there arises a substance (de novo so far as our knowledge now 
goes) which inhibits the activity of the enzyme, and thus the accumulation of 
homogentisinic acid up to 20 per cent. is indirectly permitted This new sub- 
stance is called anti-enzyme. For different organs of the same individual and for 
different individuals of close systematic relationship this anti-enzyme is identical. 
With decreasing relationship, however, the actual substance. of the anti-enzyme 
seems to differ, though the function remains constant. Chloroform narcosis, 
: : ; ni 
silver oapreriil siterulatides’ is a safe and reliable test for tropistic sensation.—Ray- 
MOND H. Ponp 
Behavior of liverworts in darkness.—Nemec has been experimenting with 
certain bryophytes which will grow in darkness and are not geotropic, to see 
what light they can throw on the mode of perception of geotropic stimulus, the 
biological significance of etiolation, and spontaneous nutations.'¢ He er- 
ent species behave very differently in darkness; some do not grow, others make 
a little growth but show no etiolation, while yet others grow long and vigorously 
and become markedly etiolated. Of the last, most are geotropic and grow erect 
or obliquely upward. But Lejeunea bidentata and L. serpyllifolia are a 
having no starch or other statoliths. In darkness their shoots are completely 
unoriented, being at first hyponastic and then nutating irregularly. The same 
disorientation i is observable in the sporogone of Aneura pinguis, but the vegetative 
shoots are geotropic and contain abundant statolith starch. The sporogone of 
Pellia calycina behaves similarly, but is slightly geotropic at first, losing this 
during elongation of the seta, which contains still some starch diffused between 
cell wall and vacuole and of slight mobility. The sporogone of Pellia epiphylla, 
on the contrary, is strongly geotropic and has abundant mobile starch. The 
sporogones of the three last named are strongly positively phototropic, and the 
reaction is in no way connected with the capsule upper part of the seta 
may be cut off, neither wound shock (which is transient) nor removal interfering 
with the reaction. The vegetative shoots of Pellia calycine grow well (plagi- 
14 NEMEC, B., Die Wachsthumsrichtungen einiger Lebermoose. Flora 96: 409- 
450. gs. g. 1906. 
