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from beginning to end of his research detailed in that paper, I must 
beg permission to offer on his behalf two remarks on the explanatory 
paragraph in question. 
1) Priority of discovery according to the established rule dates 
from the day of publication of a paper. As Prof. Leuckart’s account 
of his completed research was given to the world on Oct. 9th 1882 in 
the Zoologische Anzeiger and Prof. Thomas’ on the following 
Oct. 19th in Nature, ten days priority in publication must be conceded 
to Prof. Leuckart. But it must not be forgotten that a peculiar 
Cercaria was discovered in Limnaeus truncatulus on Dec. 22nd 1880, 
described in April 1881, in the Journal of the Royal Agricultural So- 
ciety, and ascribed explicitly to Fasciola hepatica by Prof. Thomas 
on grounds that were absolutely convincing to him and (I may add) to 
myself who were both personally acquainted with the whole evidence 
available on the subject. The crucial test of experimental breeding 
was only required to convince the world: and this proof would have 
been forth-coming in 1881, had not every endeavour to procure L. 
truncatulus failed in a manner most unfortunate. In 1882, however, 
the additional evidence desired was furnished independently, by Prof. 
Thomas in England and Prof. Leuckart in Germany, within a ten 
days interval. Priority in discovery of the Cercaria dating from April 
1881 must certainly be conceded to Prof. Thomas and I must protest 
in the strongest possible manner against any idea that it was merely a 
happy suggestion on his part to couple that special Cercaria with Fas- 
ciola hepatica It was a sound logical conclusion based on a thorough 
pains-taking investigation of a singularly limited area where an out- 
break of Sheep-Rot had occurred at the village of Wytham within easy 
walk of Oxford. It was in the strength of his conviction that Prof. 
Thomas applied to the Royal Agricultural Society for an additional 
grant when he found his funds exhausted early in 1882; and his friends 
supported his application from a conviction on their part of his assured 
ultimate success. The additional sum thus obtained, I need hardly say, 
enabled him to conduct his experiments to a triumphant conclusion at 
the end of August in the same year. 
2) To say that Prof. Thomas’ paper published in January 1883 
is vessentially a confirmation only of Prof. Leuckart’s facts already 
published at earlier dates« appears to me and to other friends of Prof. 
Thomas nota little misleading. The paper on the contrary while it 
incidentally confirms Prof. Leuckart’s results, is also essentially 
confirmatory of Prof. Thomas’ own facts previously published in 
1881 and 1882. It is an illustrated expansion of the article in Nature 
before mentioned enriched with stores taken from earlier papers. Mo- 
