THE CEYLON PEARL-OYSTER. 297 
From the first of these specimens the following preparations 
were made :— 
(a) Preparation XX VII, a piece of tissue cut from the border- 
land between the mantle and the adductor in the first of the 
above specimens. This piece measured about 7x5 x 4 mm., and 
contained 36 small pearlsand numerous so-called “calcospherules.” 
The preservation was so bad that no differential staining of 
the soft tissues could be obtained, all parts reacted alike to the 
stains used. [Preparation XXVII (Pls. XXXVIII., XXXIX. 
figs. 19-21, Pl. XL. figs. 24—27.)] 
(b) Preparation XXIX was a piece of the mantle of the same 
individual near themargin, containing 17 so-called“ calcospherules,” 
one of which is becoming coated over with nacre (Pl. XX XIX. 
figs. 22 & 23). The figures were made from the whole object— 
fig. 22 representing it as it was before decalcification, fig. 23 after 
it had been decalcified ; both as seen when cleared with oil of 
cloves. The preparation was then sectioned, but the state of pre- 
servation did not allow of the relations of the “ calcospherules ” 
to the tissues being investigated in this instance. A piece of 
tissue was also cut from the second of these specimens, decalcified, 
examined entire, and sectioned. It contained about 20 small 
pearls and numerous so-called “ calcospherules.” [Preparation 
XXIV.| 
Forty pearls, of varying sizes, some lying loose in the bottoms of 
the jars containing the specimens, others taken from the tissues, 
were decalcified and examined in oil of cloves. Of these, six were 
sectioned and further examined. [Preparations XXIII, LXIIT 
(a, B, & L), and LXVI (4&1) (Pls. XXXIX.-XLI. & XLIV. 
figs. 21 a, 28, 31, 32, 49).] 
All the pearls from these specimens I refer to the class called 
by Herdman ‘“ Muscle-Pearls.” 
(iv.) Three Specimens of the Pearl-Oyster collected by Professor 
Herdman in 1902. 
Prof. Herdman, at the request of the Ceylon Company of 
Pearl Fishers, Ltd., very kindly allowed me to examine his 
material (see (v.) below) and handed me three specimens of the 
Pearl-Oyster, each of which contained a small “ muscle-pearl ” at 
the point of insertion of one of the levators of the foot. The pieces 
of tissue containing these three pearls were cut out, decalcified, 
and sectioned [ Preparations IV, VI, and VII (Pl. XX XV. fig. 8) |. 
Although these specimens had, apparently, been preserved 
in formalin, which is not the most satisfactory preservative for 
histological purposes, they showed quite a lot of histological 
detail, and enabled me to form some idea of the mode of origin of 
muscle-pearls, and of the curious cyst-like bodies which precede 
them. 
(v.) Professor Herdman’s Slides. 
As stated above, Prof. Herdman very kindly allowed me 
to examine his slides, which he sent to me a few at a time. 
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