270 DR. H. LYSTER JAMESON ON 
material. Details of the morphology and histology were 
then worked out, and the relationship which the larve bear 
to pearl-formation was investigated.” 
Strange to say, Professor Herdman’s Preliminary Report to 
the Government, dated July Ist, 1902 (18), makes absolutely no 
reference to the discovery in the previous March of this important 
aspect of the parasites of the Pearl-Oyster. 
In the Preliminary Report referred to, Prof. Herdman says 
(p. 2): 
‘Samples of all the oysters obtained by us were examined 
for parasites and for any diseases or abnormal conditions, and 
although a considerable number of minute parasites, both 
Protozoan and Vermean, were found, still that is by no 
means unusual amongst molluscs, and we do not consider 
that we saw anything which gave evidence of any epidemic 
disease or widespread and injurious prevalence of parasites.” 
And again in the same Report (p. 4), in his summary of 
conclusions, the Professor says : 
“A considerable number of parasites, both external and 
internal, both Protozoan and Vermean, were met with, but 
that is not unusual in molluses, and we do not regard tt as 
affecting seriously the oyster population.” (‘The italics are 
mine.) 
Tn view of the last three quotations, if it were not for the very 
definite assertions in Part IT. p. vi, and Part V. p. 6, of Professor 
Herdman’s full report, quoted above, I should be almost inclined 
to think that, while the Cestode larvee were no doubt discovered 
“in association with pearls” during Professor Herdman’s cruise, 
the Cestode theory of Pearl-formation might have been evolved 
after Professor Herdman’s return to England, and after the above- 
mentioned preliminary report had been submitted. In that case 
Mr. Hornell might well have been misled by the false analogy of 
the case of the Trematode origin of pearls in A/ytilus, which was 
dealt with at length in my paper (25). This paper appeared 
in August 1902; that is to say shortly after the Professor’s pre- 
liminary report of July Ist, 1902, containing no reference to the 
Cestode theory, was submitted. The view that my paper might 
have misled Mr. Hornell and Professor Herdman would also derive 
support from the fact that the real point of my paper had apparently 
been missed, viz. that it is not the presence of any parasite, but 
the specific stimulation of a narticular kind of parasite that 
causes the growth of the pearl-sac. I consider this point is by far 
the most important contribution I have so far made to the subject, 
and I believe it will be the basis upon which a rational system of 
artificial pearl-production will ultimately be built. 
The first announcement of Prof. Herdman’s theory of Pearl- 
formation seems to have been made at a lecture delivered before 
the Royal Institution on March 27th, 1903, an abstract of which 
appeared in ‘ Nature’ for April 30th of the same year (14). 
[12 
