46 
Kryptogamen Floravon Sachsen, der ober Laisitz, Thuringen, 
und Nordbihmen. Dr. L. Rapenuorst. 1868, 
Beitrage zur néheren Kenntniss und verbreitung der Algen. 
Dr. L. Rasennorst. 1863. 
Flora Europea, Algarum Aque dulcis et submarine. Sectio 
1. Algas Diatomaceas complectens. Dr. L. RaBENHORST. 
1864. 
Ueber neue oder ungeniigend gekannte Algen. A. Gruxow, 
Verh. der Akad. Wien, 1860. 
Die Osterreichischen Diatomaceen. A. Guunow, Verh. der 
Akad. Wien, 1862. 
Ueber einige neue und ungeniigend bekannte Arten und 
Gattungen von Diatomaceen. A. Grunow, Verh. der 
Akad. Wien, 1862. 
Tue advance that has been made in the pursuit, of micro- 
scopical science during the last few years, stimulated by im- 
proved and cheaper instruments and the advantages observers 
have over their predecessors in good introductions to the 
various branches of study, has, im no field, been greater than 
in the investigation of the microscopic forms of Alge. Of 
these the special favorites have been that class whose sili- 
ceous skeletons afford, in many cases, such beautiful objects 
for mere admirers of the wonders of nature, whilst the eluci- 
dation of their modes of structure, propagation, and growth, 
are equally attractive to the scientific observer, and afford 
some of the most difficult problems of microscopical study. 
This tribe or class of Algze, known as the Diatomacez, has 
for many years occupied the attention of observers, both in 
Europe and America. ‘Their indestructible siliceous skele- 
tons are found in abundance in every quarter of the globe, 
every pool contains its species. Rivers, seas, and lakes, are 
ich in characteristic forms. The Polar seas abound with 
them to such an extent that cases are recorded of soundings 
being almost wholly composed of their remains. We find 
them at the lowest depths of the Atlantic, and on the edges 
of the newest-formed coral reefin the Tropics. We meet with 
them in abundance in the Himalayas and the Alps, and in 
Germany, America, and many other localities, whole strata 
beneath the surface of the earth consist almost entirely of 
the indestructivle remains of these minute organisms. 
it is no matter of surprise, therefore, at the present day, 
when microscopes of good working capabilities are easily 
obtainable at a moderate cost, that such universally dis- 
tributed objects should be one of the most attractive studies 
