304 
POPULAH SCIENCE PEYIETV. 
Plowright, who gives an account of the w^ork says, that its first fasciculus, 
comprising specimens of fifty species of those fungi which exert a baneful in- 
fluence upon agriculture and horticulture, and also those which take part 
in the administration of household economy, has just been published. The 
aim of the editor has been to give ample and characteristic specimens in 
crder that the study of those species of fungi which are hurtful to our cul- 
tivated plants or forest trees may be facilitated, as it is only in this way 
that we can hope to combat the ravages of our numerous enemies. Conse- 
quently the greater portion of this fasciculus consists of those species which 
have their abode upon living plants. Puccinice, Uredines, and Peronosporae 
find several representatives. Amongst the more interesting species con- 
tained in this fasciculus are, JJreda sorghi (Pers.), Puccinia Helianthi 
(Schw.), P. maydis (Potsch.), Ustilogo destruens (SchL), TJredo cichorace- 
arum (D.C.), var. Endiv(^, Pliacidmm medicaginis (Lasch.), Pxoascus 2)runi 
(PckL), Septorin olece (D. & M.), Septoria Mori (Lev.), Hysterium nervise- 
quum (D.C.), Oidium lactis (Fr.), Succharomyces ajnculatus (Pees), and 
-Several others. The specimens are very good in quality and abundant in- 
quantity ; each species being enclosed in a separate paper wrapper, their 
examination is greatly facilitated. Upon the whole, the author, Baron 
Thuemen, must be congratulated for the eminently practical turn this pub- 
lication gives to the study of Fungology. 
The Self-division of Diatoms. — Professor Smith writes lately to the' 
editor of the “ Lens,” saying : — It may be objected that if by self-division 
the frustules become smaller, then the persistent filamentous forms, at least 
some of them, should, upon measurement, actually exhibit this gradation in 
size.” I reply that this is the case, and in a filament of thirty-seven double 
frustules of a large Melosira moniliformis, I find the middle frustules 
larger by -0001'' (with the objective 30 divisions of my Powell and Lea- 
land thread micrometer), and so repeatedly of other chains of frustules. It 
would at first appear that the largest frustules should be at the ends, and 
not the middle of a filament. We must remember, however, that although 
the two larger primary valves may be carried to the ends if the filament 
remains unbroken, yet all the time self-division is occurring between j so 
that a series of nodes, or swellings, will exist all along the chain. For 
example, if after the formation of, say, half a dozen frustules, so nearly the 
same siz:e that we may consider them equal, we now suppose self-division 
to occur simultaneously, so that each frustule produces six others, then 
these latter, smaller than the older ones, would be distributed throughout 
the chain, and these again, all simultaneously dividing, would give rise to 
still smaller ones interposed ; and it is manifest that a chain would very 
likely be severed at the smaller frustules, and the partial filaments would 
have the larger and older (perhaps thus more siliceous) frustules, near tho 
middle, unless we should chance to find one of the ends with the valve of 
the primary frustule, which would rarely happen. 
A new British Nitophyllum has been found. “ Grevillea ” for January 
says that Dr. J. E. Gray has drawn the editor’s attention to a recent and 
valuable memoir by J. G. Agardh, entitled Bidrag till Florideernes Syste- 
matik,” with which algalogists in this country should make themselves 
acquainted. Apart from the new and systematic arrangement of tho 
