744 
Journal of A gricultural Research voi. xxvn, no. io 
prophase or early metaphase. Seven chromosomes are at the equatorial 
plate, some even having divided, while the remaining 7 are lagging in their 
approach to the plate. It is these laggards that cause observed irregular¬ 
ities in this and the homotypic division. They are again tardy in their 
movement from the nuclear plate and may not be included in the daugh¬ 
ter nuclei and so the resulting pollen grains do not receive either a quali¬ 
tatively or quantitatively equal amount of chromatin material. This 
type of reduction is styled as irregular. 
The chromosome number of varieties White Queen and All Summer 
21 
seems to be —* During meiosis they show many of the irregularities 
Li 
peculiar to triploid hybrids, and, consequently, they are grouped with the 
foregoing polyploidous raspberries. The pollen of these two sorts, how¬ 
ever, seems remarkably good when their chromosome condition is con¬ 
sidered. 
R. strigosus X R- idaeus, (?). Horticultural variety Erskine. This originated at Tee, 
Mass., with E. J. Norman, being found in 1895 among Marlboro plants set in 1890. 
Two other varieties, the Cuthbert and Golden Queen, were being grown by Norman 
at that time. As the plant w T as small, he supposed it to be a seedling of the Marlboro. 
The Marlboro plants were obtained from Ellwanger & Barry of Rochester, N. Y., who 
also were growing Fontenay and other European raspberries. Fontenay is an autumn- 
fruiting sort and probably belongs to this polyploid group. There is a bare possibility 
that Erskine may have come from that source. If the assumption that Erskine origi¬ 
nated from the Marlboro is correct then it is the only polyploid variety of American 
origin derived from American varieties yet found. 
Horticultural variety La France X Ranere. These hybrids were made by 
the junior author at the Bell Horticultural Field Station and two of the seedlings, one 
entirely sterile, the other nearly so, were selected for this study. 
Erskine was the second polyploid raspberry discovered and difficulty 
was experienced in finding good mitotic figures to study the various 
phases of this form. This supposed hybrid is triploid, and the reduced 
chromosome number is represented in Plate 3, D. There are generally 10 
chromosomes at diakinesis. In the earlier study of the Eubatus subgenus 
by the senior author, triploid forms were found to be very abundant, and 
this hybrid behaves in a manner very similar to that described for triploid 
blackberries. Seven of the bivalent chromosomes behave in a regular 
manner during the reduction phases, but the remaining chromosomes are 
slow about fusing in the heterotypic prophase. These laggards are dis¬ 
tributed, during meiosis, in an irregular manner to the four daughter 
nuclei or are frequently extruded into the cytoplasm where they degener¬ 
ate or become the nuclei for dwarf pollen grains. 
The hybrid, La France X Ranere, is triploid, which would be the 
natural result if the parents contributed 14 and 7 chromosomes, respec¬ 
tively. Plate 3, A, B, and C, represents prophases of the parents and the 
hybrid. This opportunity to study an Fj raspberry hybrid has shown 
that it behaves in a manner very similar to that described by Rosenberg 
(15) for the well-known Drosera hybrid. This artificially produced rasp¬ 
berry hybrid has all the irregularities of chromosome distribution noticed 
in triploid blackberries, and furnishes additional evidence that many of 
our blackberries are very recent hybrids. 
In collecting material of this La France X Ranere cross, buds were 
gathered from two seedlings, No. 1 and No. 2. All anthers of No. 1, as 
pictured in Plate 1 ,C, were so sterile that it was impossible to find normal 
reduction phases. Such extreme sterility recalls the sterility of Prunus 
cerasus X P. avium as reported by Dutrochet (7) who writes, 44 The 4 stamina’ 
