326 
Fig. 7. Micro-sclerotia germinating under conditions similar to 
those described under 5, and producing similar 
sporules; x 400. 
». 8. Large brown, thick-walled cells germinating in 
nutrient solution with free access of air, and deep 
the form of fruit known as Dematium pullulans ; 
0. 
FY Sporules of the Dematium increasing by gemmation ; 
x 400. 
y ^29. Runs of sporophores of Cladosporium producing a 
slender form of Dematium pullulans ; 
, ll. A form of Macrosporium often- appearing on old 
eg di caused by the Cladosporium. N 
netic connection between the two could be 
entautlahiod $ x 400. 
» 12. Spore of the Macrosporium germinating ; x 750. 
G. MASSEE. 
DCXXXIL—THE ADVANCES MADE IN AGRI- 
CULTURAL CHEMISTRY DURING THE LAST 
TWENTY-FIVE YEARS. 
An important address has been recently delivered by Professor 
MAERCKER, of Halle, to the German Chemical Society (Ber. 1897, 
summarising the advances which have been made in 
agricultural chemistry during the last twenty-five years. Professor 
aercker pointed out that the term Agricultural Chemistry meant 
more at the present time than the mere application of chemistry 
to agriculture, as shown by the fact that the agricultural chemist, 
in his efforts to assist the farmer, was often more concerned with 
the biological sciences than with chemistry ; ; while, in addition to 
his purely scientific work, he was required to take account of 
II. Soils and Manures; III. Artificial Selectio It repro 
duced here by the kind permission of the Editor | of the pee 
Institute Journal. 
I. PLANT-FOOD. 
In pt bn nourishment to plants we must know what 
substances are necessary, and in what form and quantity they 
should be pro videt. Little progress was made in our knowledge 
of the subject till the quite recent introduction of the method of 
water-cultures of Sachs, Knoop, and Nobbe and the method of 
sand-cultures of Hellriegel permitted of the conduct of experi- 
ments in pure media, and thus rendered it possible to ascertain 
not only what substances are essential for plant life, but also the 
