298 PROCEEDINGS OF SOCIETIES. 



moved -^^ of an incli to three revolutions of the cutter, and, as the 

 latter was nearly ^ of an inch in diameter, this was equivalent to a 

 straight draw of three inches for every ^J^ of an inch cut : this relation 

 was attained mechanically. Great speed was not recommended. The 

 object was supported on a little ebonite block capable of motion round 

 an axis for the adjustment of the object to be cut in a vertical plane. 

 The machine was of very diminutive size and delicate construction. 



A paper was read by Dr. D. Moore " On the Generative Processes 

 of the Cockle {Cardium edule), Mussel {Mytilus edulis), and the Oyster 

 {Ostrea edulis)." He first drew attention to the difference of opinion 

 on the subject, by contrasting Professor Owen's statement of twenty 

 years ago with Professor Eolleston's more recent statement in 1870 ; 

 Professor Owen asserting that all Lamellibranchs had the sexes in 

 distinct individuals, Professor EoUeston excluding Ostrea and Cyclas, 

 which had the sexes united in one individual. He stated that his 

 observations had led him to the conclusion that the cockle and the 

 mussel were also truly hermaphrodite, having the sexes united in one 

 individual. He then proceeded to give an outline of the minute 

 anatomy and general distribution of the generative gland in the 

 cockle, mussel, and oyster, stating that all the steps from a gland 

 containing immature sperm cells to one containing perfect eggs in the 

 oyster, and eggs and young in the cockle and mussel, could be 

 clearly traced — the glands containing spermatozoa being only a stage 

 in the history of the gland containing eggs or young. He then drew 

 attention to some diagrams enlarged from camera-lucida di-awings, 

 showing three principal stages in the history of the gland : — 1st, 

 when the gland contained imperfect spermatozoa ; 2nd, when it con- 

 tained perfect spermatozoa and clear cells, the entrance of the sper- 

 matozoa into the clear cells, which he had observed in the cockle, 

 constituting the impregnation, which led to the 3rd stage of well- 

 formed and easily recognizable eggs. In the case of the cockle and 

 mussel, the eggs were hatched inside the animal, and the young were 

 brought to maturity in a system of tubes, which were much more 

 developed in the cockle than in the mussel. In these tubes the 

 young were found in all stages of growth, with a number of yelk 

 balls which doubtless supplied them with nourishment. The young 

 were figured in the diagrams, special attention being directed to 

 the stage at which they were extruded from the parent, when they 

 constituted a true larval form, and possessed a rudimentary shell. In 

 the oyster the eggs were extruded from the generative gland into the 

 buccal pouch, between the palpi and the layers of the branchiae, 

 where they remained surrounded by a gelatinous substance, until they 

 were developed into freely moving ciliated young, when they were 

 puff'ed out from the parent shell a small number at a time. Dr. Moore 

 concluded by stating some general considerations which he thought 

 pointed in the same dii-ection as his observations on the generative 

 processes in these animals. 



This paper was further illustrated by various preparations, which 

 were exhibited at the close of the meeting. 



