346 REPORT—1904. 
The additional grant obtained from the Association has been expended 
in providing mounts and binders for storing the photographs, and also 
for the purchase and printing of cards to make a classified catalogue, in 
addition to the Register. The completion of this catalogue has occupied 
some considerable time on the part of the Secretary, but it was felt that 
the catalogue would make the collection more serviceable by facilitating 
reference to any particular photograph. 
As some inquiries have been received regarding the photographs 
which have already been registered, the Committee suggest that the 
list of photographs now registered might be printed by the Associa- 
tion and circulated among members of the Association, corresponding 
societies, and donors of photographs. By this means the usefulness of the 
Register would be increased, and the owners of photographs of botanica! 
interest would become acquainted with the scope of the Register, and would 
also learn what photographs might usefully be added to the list. 
Kuperimental Studies in the Physiology of Heredity.—Report of the 
Committee, consisting of Professor H. MarsaatL Warp (Chair- 
man), Mr. A. C. SEwarp (Secretary), Professor J. B. FARMER, 
and Dr. D. Sarr. 
Report to the Committee by W. Bateson, M.A., FBS. 
In January 1904 Mr. R. C. Punnett, Fellow of Gonville and Caius 
College, came into partnership in these experiments, and from that date 
the work has been carried on jointly. The Sweet Pea work has been done 
jointly with Miss Saunders also. Besides poultry and sweet peas, on 
which we now report, preliminary trials with other subjects are in 
progress. 
I. Pouttrry.—Colouwrs.—Some complex cases are under investigation, 
and respecting these a report is deferred. 
The case of the Andalusian fowl has been studied in detail. It appears 
that the typical blue colour is a heterozygous character, the gametes 
bearing black or a splashed white in approximately equal numbers. The 
extracted black is pure. The white probably can split again, giving off a 
purer white. 
The colour, Brown-breasted, with purple face, is dominant over Black- 
breasted (practically Gallus bankiva) strongly in 9 2, weakly in oo. 
The segregation, judged on the down, is nearly perfect. The adult 
colours are not yet worked out. 
Combs.—The relation of the four forms, rose (7), pea (p), rose-pea 
(rp)= Malay ‘ Walnut,’ and single (s) has formed a main subject of our 
work ; 7 and p are each dominant over s ; 7 Xp gives rp ; rp is dominant 
over all. 7p, whether formed directly by crossing pure 7 x pure », or 
indirectly by crossing rs x ps, gives off four types of gametes, 7, p, 7p, 8, 
in approximately equal numbers. The origin of s here is uncertain. It 
seems to be connected with the failure of segregation in the case of the 
rp gametes. rpxrp therefore produces ten actual types of birds, dis- 
tributed thus in appearance, 9rp, 37, 3p, 1s. rp xs gives on an average 
equal numbers of all four visible types. Of the five possible types of rp 
birds, four have been found experimentally. It is not yet known if 
