JOURNAL OF PROCEEDINGS. 



1(37 



M. pusilla, it is 2-4 times as large as the seed. In the large edible fruits of 

 Cerei, such as C. triangularis, C. grand ifonis, C. gtganteus, etc., it consti- 

 tutes by far the largest part of the fruit. The cells are globular, oval, or 

 variously compressed ; in some species I find them extremely small, 0.01- 

 0.03 1. long, while in others they are 0.1-0.2 and even 0.3 1. long. 



The genus Opuntia apparently differs in having the whole seed covered 

 with juicy cells, which, in size and quantity, vastly predominate over the 

 cells of the rather insignificant funiculus proper. But the whole bony 

 coating of the seed being but an arillary enlargement of the funiculus, 

 (Cact. Mex. Bound., p. 70,) this peculiar case entirely falls into the 

 analogy of the other Cactacece. The real difference is caused by the 

 nature of the arillus, which, getting extremely hard, leaves the cells of 

 the epidermis only to grow out, and finally to form the pulp of the fruit. 

 Soon after fecundation these cells gradually become elongated, cylindiical, 

 and disconnected among one another, rising perpendicularly from the 

 surface of the seed; they are shorter, of nearly equal length, and per- 

 fectly straight, on the faces of the young seed, and longer, hair-like, 

 and twisting in different directions on and near the rim. In O. g l £u- 

 cophylla, which I take to be a mere variety of O. Ficus Indica, I find 

 them at their first appearance on a seed of less than one line in di- 

 ameter only about 0.00-1 1. long and wide; on the rim they soon grow 

 to twice the diameter and ten times the length, till at maturity the larger 

 ones are 0.3-0.5 1. long. These cells, at first simple and cylindrical, 

 become at last jointed and clavate, the terminal cell3 being many times 

 larger than the basal ones, thus properly fillins; the interstices between 

 the seeds. During winter, the fruit and seeds having reached their full 

 growth, these cells contain a colorless, viscous, insipid fluid ; in the 

 following spring, when the fruit has assumed a deep purple colour, and 

 attained full maturity, they contain a sweetish, purple liquid, and 

 soon separate, forming what is properly called the pulp. The single 

 cells are mostly oval or oblong, 0.02-0.20 1. in length. I find the same 

 structure in O. Eugelmanni, which, however, ripens its fruit, with us, 

 in autumn, and it undoubtedly obtains in all OpuntiBe with large and 

 juicy fruit. . . 



In O. Rafincsquii, and probably in all species with less juicy fruit, the 

 cells on the face of the seed are not developed, only those on the rim 

 producing; the pulp, which in this species as well as in O. vulgaris and 

 O. Pes Corvi, remains, even at full maturity, insipid and viscous and of 

 pale red colour. In this condition the fruit adheres to the plant, without 

 any change, until it falls off in the following spring. 



In O. Brasilieniis and O. monacantha these epidermis-cells are greatly 

 elongated, forming, in fact, a matted, tough beard, 2-3 lines long, analo- 

 gous to that of the unripe cottonseed; each hair consists of several 

 slender joints, 0.01-0.02 1. in diameter, the terminal one often thickly cla- 

 vate or' otherwise variously inflated. I have found them thus in the 

 unripe fruit late in autumn ; how they may change at maturity I have 

 been unable to ascertain. 



No such development of the epidermis-cells seems to take place in the 

 Opuntiaa with dry fruit, such as O. Missouriensis, O. clavata, etc. ; the 

 seed, consequently, has a whiter, polished, ivory-like surface, while that 

 of the juicy Opuntise fruits is dull and almost rough, and not so white. 



The cells of the parenchyma of the fruit, as well as those of the bony 

 seed-coat, are full of aggregations of crystals ; those of the funiculus 

 proper contain fewer and smaller clusters ; but in the pulp itself I have 

 never seen them; neither could I discover any in the parenchyma, or in 

 the pulp of the fruits of Mamillariaj. 



Dr. J. S. Newberry, of Cleveland, O., and Prof. Chas. T. 

 Jackson, of Boston, Mass., were elected Corresponding Mem- 

 bers. 



