830 ON THE HABITS OF SPECIES OF LEMN&. 
Estimates of Pond and Ditch Temperature for the week preceding 
Germination, etc. (Fahr. scale). 
Obs. Species. Date. Mean Temp. aioe 
Germination, | L. minor *. Early in Febr. 40° 45° 
Budding in | 7. minor, Early in Febr. 40° 45° 
spring. 
” L. gibba. Febr. 45-46° 51° 
» L. polyrrhiza. | Early in April. 52-53° 60° 
Full develop-| L. gibba. May. 61-62° 69-70° 
ment of the 
summer plant.) L. polyrrhiza, | May. 62-638° 70° 
Flowering. L, minor, June. 65° 72-73° 
» L, gibba. July. 73° 80° 
Death of the - End of October or 
summer plant. L, polyrrhiza. early in Noy. a Under 50° 
* In a previous spring the seeds of Lemna minor germinated at the latter 
part of February, but no temperatures were recorded. Mr. W. Wilson 
(Hooker’s Botan. Miscell. vol. i. p. 145) regards April as the usual time for 
the germination of the seeds of Lemna gibba, but he experimented on some 
which had been kept dry throughout the winter. 
Nore, Sept. 12th, 1894.—I have since learned that Micheli 
described the flowering of Lemna gibba in language similar to my 
own (Journ. de Phys. tome 82, p. 107). This plant has behaved 
very differently during the cool and unsettled weather of the 
past summer. The gibbous fronds did not appear until early in 
July, and very few flowered, showing only the pistil, as before. 
No winter flat fronds have been developed. A recent experi- 
ment has proved that Lemna polyrrhiza is able to go through all 
its stages of growth on wet mud. Winter fronds placed on wet 
mud in March gave rise to the characteristic summer plauts, 
which in their turn are now producing the winter fronds.— 
H. B. G. 
