84 NATURAL SCIENCE. Feb., 



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 theAimals of Botany \s 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 Stenogvamme interrnpta. 



Alg/E. 



The 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 Sac. PJiysiograph. Lund., vol. xxviii., 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 Algae (including such contemporaries as Nordstedt, 

 Kjellman, Areschoug) is only paralleled by the past generation of 

 Britons, which gave us Harvey, Greville, Ralfs, &c. Criticism, 



