Bucephalus to the cockle. 65 



I have mentioned these features chiefly to invite the comparison of 

 other observers. 



In conclusion : there are two points upon which I do not feel 

 quite certain that I understand M. Lacaze-Duthiers' views. I 

 think he indicates his belief that a tube is a sporocyst, a mother, a 

 larva ; and he speaks of the tubes as " unrolling themselves." I do 

 not find this. Neither, if the eggs are found both in the ovisacs 

 and in the tube, can I disconnect the two, nor think of the tube other- 

 wise than as a continuation of the genital canal. Again, he speaks of 

 the Helminth as occupying principally the conduits of tbe genital 

 glands and even the interlobular spaces, and thus rendering the 

 mollusc sterile. If he refers to Bucephalus itself, I find it only in 

 tbe tube, whatever that tube may be ; whilst the indubitable 

 presence contemporaneously of eggs in the ovisacs disproves the 

 alleged sterility. 



The co-existence of lobules of eggs with the tube, supposing the 

 eggs to be those of the Cockle, and the tube a trematode or sporo- 

 cyst, disproves the sterility which Lacaze-Duthiers asserts to be 

 caused by the presence of the lattei\ If the eggs found in the 

 ovisacs be those of the parasite, then, not only has it eggs, which 

 our author denies, but, the tube ceases to be a sporocyst, and is a 

 normal uterine organ developed in connection with the ovary. 

 The results yielded by this inquiry seem to be these : — 

 Either first— The Bucephalus is the larva of the Cockle (and if 

 not, it remains an interesting question for solution, what is ?). 



Or second — The Bucephalus is a parasite ; but if so, it does not 

 render the Cockle sterile, as asserted by Lacaze-Duthiers. 



And third — The connection of the tube with the ovisacs, as 

 established by the presence of eggs in both, proves that it is not 

 an independent sporocyst, as asserted, but an organ of the Cockle. 

 Whilst fourth — If this connection be denied, though the case of 

 the 6th April seems to render it Qertain, the Bucephalus must still 

 be developed from eggs seen in the tube, in contradiction of a 

 third assertion by Lacaze-Duthiers. 



EXPLANATION OF PLATES IV. V. 

 These drawings are not made to scale, save when so indicated. The magni- 

 fying powers employed were generally 60. 170, and 310 diameters. 



A. Piece of tube (sporocyst of von Baer and Lacaze-Duthiers) showing 

 branched structure, taken from Cockle, June 14, 1872. 1 and 2 branches severed 

 in removal. 



F 



