THE CEYLOX PEARL-OYSTER. 



297 



From t,he first of these specimens the following preparations 

 were niaxle : — 



(a) Pi'eparation XXVII, 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 7x5x4 mm., and 

 contained 36 small pearls and numerous so-called ''calcospherules.'' 

 The preservation was so bad that no diflerential staining of 

 the soft tissues could be obtained, all parts reacted alike to the 

 stains used. [Preparation XXVII (Pis. XXXVIII., XXXIX. 

 figs. 19-21, PI. XL. figs. 24-27.)] 



"(?)) 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 (PI. XXXIX. 

 tigs. 22 & 23). The figures were made fi'oin the whole object — 

 fig. 22 representing it as it was before decalcification, fig. 23 alter 

 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, LXIII 

 (A, B, & L), and LXVI (A & I) (Pis. XXXIX.-XLI. & XLIV. 

 figs. 21 «, 28, 31, 32,49).] 



All the pearls from these specimens I refer to the class called 

 ])y Herdman "Muscle-Pearls." 



(iv.) 77iree /Specimens of the Pemi-Oijster collected hij 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 (PI. XXXV. 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 alloAved me 

 to examine his slides, A\hich he sent to me a few at a time. 



