TUBER-BEARING SPECIES OF SOLANUM. 507 
Secondly, a suggestion as to what might be done towards 
widening the power of climatic adaptation of the cultivated 
potato. "There are certainly six distinct species of tuber-yielding 
Solanum, each with its own distinctive climatie peculiarities. I 
went to Mr. Sutton’s trial-grounds specially to investigate this 
point, and came away fully satisfied that all the numerous vari- 
eties in cultivation had originated from S. tuberosum *, as here 
defined. As far as climate is concerned, it cannot be doubted 
that Solanum Maglia (or the Darwin potato as we might suitably 
christen it in English) would be better fitted to succeed in 
England and Ireland than S. tuberosum, a plant of a compara- 
tively dry climate. We have indisputable testimony that S. 
Maglia and S. Commersoni yield readily an abundant supply of 
eatable potatoes. What I should suggest is, that these should be 
brought into the economic arena, and thoroughly tested as regards 
their economic value, both as distinct types and when hybridized 
with the innumerable tuberosum forms. 
EXPLANATION OF THE PLATES. 
Prite XLI. 
Solanum tuberosum, from a wild specimen gathered in the Chilian Andes by 
Bridges, No. 719. 
Puare XLII. 
Solanum Maglia, from a wild specimen gathered by Darwin in the Chonos 
Archipelago. 
Prate XLIII. 
Solanum cardiophyllum, from Lindley’s type specimen, from the Chiswick 
garden, 1847. 
Prate XLIV. 
Solanum Commersoni, from a wild specimen gathered at Montevideo by Gibert. 
Prate XLV. 
Solanum Jamesii, from a wild specimen gathered in New Mexico by C. Wright, 
No. 1588. 
Puate XLVI. 
Solanum oxycarpum, after Schlechtendahl, from a wild specimen gathered 
in Central Mexico by Schiede. 
* Four old cultivated specimens in the Sloane herbarium at the British Mu- 
seum and one from Philip Miller all belong to typical S. tuberosum. 
