166 
TRANS. OP THE ACAD. OF SCIENCE. 
and on houses, but are very common, not to say universal, in our gardens 
and vineyards, in some seasons more so than in others. It is said that ' 
vineyards further north, e. g. in Northern Illinois, are free from these 
pests. 
Whether other diseases assist in the destruction of the grape, as t 
growers will have it, he cannot, from his own experienc 1 ' 
A tar i e J 
; determine. 
• seen the Erysiphe, which is so destructive to the gooseberry^ 
and to vines in graperies, on grapes cultivated in the open ground. 
Dr. Hilgard presented a series of mounted specimens of 
Algae. 
October 7, 1861. 
The President, Dr. Engelmann, in the chair. 
Six members present. 
A letter was read from A. F. Bandelier, Oct. 4, 1861, com^ 
municating meteorological observations for September, at 
Highland, Ill. 
The Proc. Boston Soc. Nat. Hist., May-August, 1861, wa^l 
received as a donation to the library. 
Dr. Shumard presented a small piece of meteoric iron from! 
Denton Co., Texas. 
Dr. Engelmann communicated the results of his investigations on the 
nature of the pulp of the Cactus fruit, illustrated by many drawings, 
Zuccarini, than whom none better understood the morphology, as well- 
as the systematic characters of the Cactacese, had already in the year 
1845 (Plant, nov., fasc. 5, pag. 34) expressed the opinion that in Cac-i 
taceae, as well as in Cucurbitacese, the funiculi assisted informing the 
pulp of the fruit. Schleiden (Grundziige, ed. 3, p. 408) ascribes the pulp 
of Mamillaria to an arillus, dissolving into single juicy cells. Gasparrini, 
in his extended but rather odd description of the Opuntiae fruit, (Osser- r 
vazioni, 1853, p. 20,) also considers the pulp as a peculiar sort of an/, 
arillus. I had long since come to the conclusion, especially after ex¬ 
amining the somewhat dry fruits of Cereus ccespitosus and Echinocadus 
setispinus , that the funiculi alone constitute the pulp, and in Cact. Mex. 
Bound., T. 20, fig. 12, I had figured the enlarged funiculi of the latter 
plant. 
The Cactus fruit is usually succulent; only some Echinocacli and some 
Opuntiae are. known to bear dry fruits. The succulent fruit consists of 
the fleshy walls of the fruit itself, originating from the carpel and the 
adhering calyx, (or part of the stem, as Zuccarini will have it,) coales¬ 
cing and forming a homogeneous mass, and of the juicy pulp, in which 
latter the seeds are imbedded. In some species the parenchyma of the 
walls, in others the mass of the pulp, prevails. The pulp is always the pro¬ 
duct of the funiculus or its appendages. The funiculus, even at the flowering 
od, bears on its inner side a beard 
period, bears on its inner side a beard of transparent fibres, 0.01-0.10 1 
in length; the fruit maturing, these fibres are enlarged, and the whole 
cellular tissue of the funiculus becomes, as it were, hypertrophic, every 
cell swelling up, filling with a sweetish, mostly red-colored juice ; at 
last the ceils in most species separate from one another, and leave the. 
seeds floating in the pulp attached only to the slender spiral vessels, 
mu i 0 f the funiculi and their proportion to the mass of the seed is 
.very different in different species ; in Lepismium Myosurus it constitutes 
only & or i of the seed ; in Mamillaria Nuttallii it bears, perhaps, a still 
smaller proportion; while in other Mamillariae, e. g. M. polylhele and 
