166 TRANS. OF THE ACAD. OP SCIENCE. 



and on houses, but are very common, not to say universal, in our gardens 

 and vineyards, in some seasons moie 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 wine- 

 growers will have it, he cannot, from his own experience, determine. 

 He has never 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, 111. 



The Proc. Boston Soc. Nat. Hist., May-August, 1861, was 

 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 Cactaceas, had already in the year 

 1845 (Plant, nov., fasc. 5, pag. 34) expressed the opinion that in Cac- 

 taceaj, as well as in Cucurbitacea?, the funiculi assisted in forming the 

 pulp of the fruit. Schleiden (Griindziige, ed. 3, p. 408) ascribes the pulp 

 of Mamillaria to an arillus, dis-olving into single juicy cells. Gasparnni, 

 in his extended but rather odd desciiption of the Opuntiaj fruit, (Osser- 

 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 acspitosus and Echinocaclus 

 selispiuus, that the funiculi alone constitute the pulp, and in Cact. Mex. 

 Bound., T. 20, fig. 12, 1 had figured the enlarged funiculi of the lalter 

 plant. . 



The Cactus fruit is usually succulent; only some Echinocacu and some 

 Opuntiaj 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 paienchyma of the 

 walls, in others the ma<-s of the pulp, prevails. The pulp is always the pro- 

 duct of the funiculus or its appendages. The funiculus, even at the flowering 

 period, bears on its inner side a beaid of transparent fibres, 0.01-0.10 line 

 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 cells in most species separate from one another, and leave the 

 seeds floating in the pulp attached only to the slender spiral vessels. 

 The ma*s of the funiculi and their proportion to the mass of the seed is 

 very different in different species; in Lepisminm Myosurus it constitutes 

 only & or 4 of the seed ; in Mamillaria Nuttallii it bears, perhaps, a still 

 smaller proportion ; while in other Mamillaria;, e. g. M. polythele and 



