MR. ANDEUSON-nENllY ON HYBRID PRIMULAS. 
17 
The spore-cells of the Alga are about the 700th of a millimetre 
in diameter, while the partly simple partly branched threads of 
different lengths vary from to -gj^. I distinguish two 
forms, which appear almost contemporaneously. In the young 
state we find mother cells arranged in a row, filled with a quan- 
tity of daughter cells. These last are elongated into threads, but 
are still surrounded by the mother cells. I have not been able 
to observe the formation of the spore-cells at present ; but I think 
it probable that the cells distinctly visible within the membrane 
of the mother cells, after its disappearance form these masses of 
spores, which I once found on the wall of a perfectly closed ca- 
vity in the stem of a Sugar-cane more than one-third of an inch 
in diameter. Even in a very small glass tube closed with a cork, 
in which I kept the yellow nests of spores, there was in moist 
weather a coating of white powder, in which I recognized the same 
spore-cells as in the watery solution. This white powder can be 
easily dispersed in the air, and can penetrate the bores of insects 
or through the root into the body of the Cane. The latter way is 
so much the easier as from the practice here of planting eyes, 
the tips of the stem with the terminal bud being for the time un- 
covel-ed, or only slightly covered, remain exposed to air and mois- 
ture. That moisture is active in the diffusion of the Alga appears . 
not only from the foregoing observations, but from the fact that 
the years in which the disease was most prevalent have been re- 
markably rainy, while in the late abnormally hot year it has almost 
disappeared. We have, then, every reason to regard this cellular 
plant as the cause of the disease, especially as at its commence- 
ment the cane vegetates strongly, and decays only at a late period, 
when the Alga decomposes the sugary juice, the masses of 
spores in the vessels hinder the flow of sap, the leaves turn yel- 
low, and the terminal bud rots. As the best remedy, I regard a 
mode of culture in future more consonant with the investigations 
of science than prevails at present in Brazil — repeated manuring 
with quicklime, as also the washing with liquid lime (lime -wash) 
the eyes or truncheons before planting. 
Y. Observations on his Hybrid Primulas, &c., in two Letters to 
Dr. Masters. By I. Anderson-Henrt, Esq. 
" I*rimulas. — As allusion has been made to my seedling flower- 
foliate Primulas (so to call them), I beg leave to forward a spike 
of one of the most advanced of that particular form. It is odd 
E 2 
