84 NATURAL SCIENCE. FER., 
be a case of hydrotropism. Thus any modification of iron which 
lessened its capacity for rusting was also found to diminish its 
attraction on Phycomyces; polished steel scarcely attracts, and 
nickeled steel not at all. | 
China clay, which is very hygroscopic, attracted energetically, 
but china showed no attraction. It has been shown that, although 
both are essentially formed of silica, agate is very hygroscopic, while 
rock crystal is not, and agate strongly attracts the filament, whereas 
rock crystal is quite inactive. The strongly hygroscopic sulphuric 
acid is also strongly attractive; certain moderately hygroscopic 
bodies, like white soap, which lose or gain moisture, according to the 
relative dampness of the atmosphere, repel or attract the Phycomyces 
accordingly. 
So great, in fact, is this sensibility of Phycomyces, that it may be 
used as a test of the presence of hygroscopic power. Having noticed 
that camphor distinctly attracted the filaments and thymol did not, 
the observer was led to anticipate that camphor is hygroscopic, and 
this, a fact hitherto unknown to chemists, was confirmed by careful - 
weighing. 
On the other hand, the roots of higher plants are positively 
hydrotropic, and, as would be expected if the author’s views held 
good, they were found to bend away from iron instead of being 
attracted by it. 
CRYPTOGAMS. 
THE same number of the Annals of Botany is also of special interest 
to the Cryptogamic Botanist. It contains a paper by Mr. Barber on 
a new fossil Alga which he has placed with Nematophycus—on perhaps 
scarcely sufficient grounds; one on the development of Champia 
parvula by Mr. B. M. Davis, an American phycologist—a capital piece 
of sound work; Professor Karl Goebel’s paper ‘‘ on the simplest form 
of moss,” read at the British Association; and Professor Johnson 
on Stenogramme interrupta. 
ALG&. 
Tue venerable Swedish phycologist, Professor J. G. Agardh, has 
earned hearty congratulations by the production of the first memoir 
of what, it is to be hoped, will prove a long series, in succession to the 
well-known Till Algernes Systematik. The Analecta Algologica is a part 
of the Acta Soc. Physiograph. Lund., vol. xxvili., and bears the stamp of 
careful and critical work on a level with the best which this great 
systematist has given us. 
The wonderful fertility of the Scandinavian school of systematic 
workers on Alge (including such contemporaries as Nordstedt, 
Kjellman, Areschoug) is only paralleled by the past generation of 
Britons, which gave us Harvey, Greville, Ralfs, &c. Criticism, 
