236 THE PULP OF CACTUS FRUIT. 
some species the parenchyma of the walls, in others the mass of the pulp, prevails. Zhe pulp is 
always the product of the funiculus or its appendages. The funiculus, even at the flowering period, 
bears on its inner side a beard 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, hyper- 
trophic, 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 mass of the funiculi and their proportion to the mass of the seed is 
very different in different species; in Lepismiwm Myosurus it constitutes only } or } of the seed; in 
Mamillaria Nuttallii it bears, perhaps, a still smaller proportion ; while in other Manillaris, 
e.g. DL. polythele and M. pusilla, it is 2-4 times as large as the seed. In the large edible [167] 
fruits of Cerei, such as C. trinngularis, C. grandiflorus, C. giganteus, etc., it constitutes by far 
the largest part of the fruit. The cells are globular, oval, or variously compressed ; in some species 
extremely small, 0.01—0.03 line long, while in others they are 0.1—0.2 and even 0.3 line 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. 76), this peculiar case entirely falls into the analogy of the other Cactacew. 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, cylindrical, and disconnected among one another, rising per- 
pendicularly from the surface of the seed; they are shorter, of nearly equal length, and perfectly 
straight, on the faces of the young seed, and longer, hair-like, and twisting in different directions on 
and near the rim. In 0. glaucophylla, which J 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 diameter only about 0.004 line long 
and wide; on the rim they soou grow to twice the diameter and ten times the length, till at matur- 
ity the larger ones are 0.3—0.5 line long. These cells, at first simple and cylindrical, become at last 
jointed and clavate, the terminal cells being many times larger than the basal ones, thus properly 
filling 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 color, and attained full miabasiny. 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 line in length. I find the same structure in 0. Engelmanni, which, how- 
ever, ripens its fruit, with us, in autumn, and it undoubtedly obtains in all Opuntie with large and 
juicy fruit. In 0. Rafinesquii, and probably in all species with less juicy fruit, the cells on the face 
of the seed are not developed, 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, viscous, and of pale red color. 
In this condition the fruit adheres to the plant, unchanged, until it falls off in the following spring. 
. Brasiliensis and O. monacantha these epidermis-cells are greatly elongated, forming, in 
fact, a matted tough beard, 2-3 lines long, analogous to that of the unripe cotton-seed ; each hair 
consists of several slender joints, 0.01—0.02 line in diameter, the terminal one often thickly clavate 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 Opuntiz with dry fruit, 
such as 0. Missouriensis, O. clavata, etc.; the seed, consequently, has a whiter, polished, ivory-like 
surface, while that of the juicy Opuntice Suited 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 Mamillariz. | 
