iy8 Blackburn and Harrison.— The Status of the British 
and is therefore tetraploid. To all intents and purposes their behaviour 
agrees with that of the pentaploids and with that of Rosa Sabini, although 
in this case only seven bivalents appear with the fourteen univalents 
(Text-fig. 5, /-i). 
V. Concluding Remarks. 
From the foregoing account it appears that in our roses the chromosome 
number upon which the various complements seem to hinge is seven, and, 
using this as a base, our local forms arrange themselves as in the appended 
table : 
Diploid. 
Rosa arvensis 
(Systylae) 
Rosa rugosa 
(Semiherbaceae) 
Tetraploid. 
Rosa pivipmellifolia (two 
forms, one sterile and the 
other fertile, as well as 
R. spinosissimd). The 
whole of the Villosae in- 
cluding Rosa omissa , De- 
segl. Rosa hybrid pirn - 
pinellifolia x ( pimpinelli - 
folia x cor iif olid). 
Pentaploid. 
All the members of the 
Eucaninae, Afzelia- 
nae, Rubiginosae, To-% 
mentosae, and one 
hybrid, Rosa corii- 
folia var. Lintoni x 
Rosa lutetiana. 
Hexaploid. 
Hybrid Rosa pim- 
pinellifolia x R. 
tomentosa var, 
sylvestris. 
As set out in the above table one discrepancy, but that glaring, exists 
between our results and those of Tackholm ; that worker finds Rosa omissa 
to be hexaploid, whereas we determine it to be quite an ordinary tetraploid 
Villosan. Luckily we are able to explain the disagreement. When satis- 
fying Almqvist’s request for British roses we included in the consignment 
three examples of Rosa Sabini (R. pimpinellifolia x R. sylvestris). All 
three were returned labelled Rosa per mollis, Almq. Now, looking up this 
name in Almqvist’s synopsis, we note that it falls under the species type of 
Rosa Acharii and in the section Villosae glauciformes, i. e. with glaucous 
hairy leaves. Ignoring for a moment that our rose is, without the shadow 
of a doubt, a. pimpinellifolia hybrid, this is demonstrably incorrect, although 
one cannot blame Almqvist for the error. We sent him specimens with the 
half-open flowers proper to an involuta form, so that its tomentosa affinities 
were masked. Judging from its prickle characters alone he was almost 
compelled to recognize in it a Villosan. Making the necessary correction 
for the section, we find that under Almqvist’s classification it runs out 
to Rosa omissa, Almq., and thus, as proved from authentic specimens, not 
of Deseglise. 1 
Almqvist’s plant is therefore a pimpinellifolia- tomentosah.ybx\d parallel 
to, if not identical with, our Rosa Sabini — a determination explaining the 
perfect agreement in hexaploidy, and the possession of twenty-eight poten- 
tial bivalents and fourteen univalent chromosomes, existing between our 
R. Sabini and Tackholm’s R. omissa. 
1 This paragraph was added after Tackhoim’s paper came to hand. 
