FEBRUARY 2, 1912] 
of whatever degree of differentiation, is greatly 
needed. 
In my discussion of “clone” as a suitable 
name for any group of plants or animals 
which has been formed from a single original 
individual by purely vegetative methods of 
reproduction, I suggested the restriction of 
the term to groups of genotypically identical 
individuals. Further consideration convinces 
me that this restriction is highly undesirable 
because it is impracticable. It would be quite 
impossible to know for a certainty that two 
twigs used as cuttings or cions from the same 
tree had the same genotypic constitution, and 
consequently there could be no security in the 
assumption that they were members of the 
same clone, if the definition given in my pre- 
vious note should be maintained. I wish, 
therefore, to offer an amendment to that defi- 
nition by striking out such restriction. The 
definition may then read: “ Clone, a group of 
individuals traceable through asexual repro- 
ductions (including parthenogenesis when un- 
accompanied by genotypic segregation) to a 
single ancestral zygote, or else perpetually 
asexual.” This definition puts the word- 
“clone” on exactly the same footing as the 
expression “pure line,” making it a purely 
genealogical term and involving no implica- 
tion whatever as to the genotypic equality of 
the individuals included in the single clone. 
zi Gro. H. SHULL 
” 
THE PRIBILOF FUR SEAL HERD 
To tHe Epitor or Science: In Science of 
October 27, 1911, page 568, there appears an 
article entitled, “The Pribilof Fur Seal 
Herd, and the Prospects for its Increase,” 
signed by OC. H. Townsend, member of the 
Advisory Board of the Fur Seal Service. 
Dr. Townsend in his article handles rather 
severely certain persons “ whose opinions upon 
the subject are of little value.” I cheerfully 
admit that I am one of the persons referred to, 
and I shall be equally frank to say that I am 
sorry Dr. Townsend feels the way he does, for 
at the bottom we both desire the same thing, 
namely, the rehabilitation and preservation of 
the fur seal herd. 
SCIENCE 
183 
A scientist who desires his opinions upon 
any subject to be of value must, above all, be 
accurate as to his facts. In his article Dr. 
Townsend tells us that “The hook-worm is 
one of the contributing causes to heavy an- 
nual losses among the young seals born on 
sandy areas.” 
In view of this statement, I would like to 
call Dr. Townsend’s attention to the report of 
Walter I. Lembkey, agent in charge of the 
Alaskan Seal Fisheries, dated December 14, 
1906 (page 274), printed as Appendix A to 
Hearings on House Resolutions No. 73: 
Inquiries have been made recently of the De- 
partment concerning the present effect of Uncin- 
aria on the seal pups, and it has been strongly 
intimated by certain persons that thousands of 
pups die annually from the ravages of this para- 
site, of which no report is made in the agent’s 
report. The fact is that Uncinaria has not now, 
nor has had for several years past, any known 
existence on the islands. This statement is justi- 
fied by actual and careful examinations during the 
last three years. 
Also to the report of Marold Heath’s 
“ Special Investigation of the Alaska Fur 
Seal Rookeries, 1910” (same publication as 
cited above, page 1223) : 
In earlier times the ravages of the parasitic 
worm Uncinaria were especially noticeable on the 
Tolstoi sand flat and portions of Zapadni; but in 
recent years, due to shrinkage of the herd, these 
areas have been abandoned. Very few cases were 
noted by Dr. Chichester in 1909, and not one was 
detected this year. The dead pups dissected were 
seemingly in a perfectly normal condition, their 
emaciated appearance and empty alimentary canal 
indicating death from starvation. 
On the question of the closed season Dr. 
Townsend is especially severe. He tells us 
that a cessation of slaughtering seals would 
be “positively dangerous,” because of the 
rapid increase in fighting males. I once made 
the suggestion to him, favorably received at 
the time, that as the old bulls haul out on the 
breeding grounds some ten days in advance of 
the females, it would be rather a simple mat- 
ter for the agent in charge and his Indians, 
armed with a few modern rifles, to dispose of 
these dangerous surplus bulls. But a far 
