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Show 1889.] ANATOMY OF GONATUS FABRICII. 131 surfaces of the pads. This idea is supported by the observations that in some sections the pads could be seen firmly pressed together with a thin line of structureless material between them. The fusiform or rod-like bodies within the cells might be compared with the structures found in those cells of Cercaria which secrete the cyst (cellules a batonnet) •**. The suggestion just made with regard to the function of the funnel-organ is by no means free from difficulties. Of these the most serious is that it persists in the adults of those forms which have a well-developed valve in the siphon. Its discharging one function in the embryo is not necessarily, however, a bar to its having some different use in the adult. The objection that in those embryos in which it is well formed (Sepia, Loligo) there is a valve in the funnel, may be answered by the hypothesis that in these small animals the valve is inadequate. I have seen some sections of Sepia in which the valve would certainly be quite insufficient to close the lumen of the funnel, unless this latter were to contract very considerably by its own proper musculature. Another weighty argument which may be raised is, that this seems a circuitous mode of obtaining the end desired, that if a valve is to be developed it would be best to have it ready for use by the time the embryo quits the egg. Nothing in the way of proof can be urged against this, but it may be remarked that natural processes often seem to us at first sight to be very roundabout in their way of operation. The whole subject is well worthy the attention of any observer who has the opportunity of working it out more thoroughly on fresh material. XII. General Conclusions. The information now in our hands for instituting a comparison between Gonatus and its nearest allies Onychoteuthis and Enoplo-teuthis may perhaps be most conveniently summed up in the form of a table. For a number of facts regarding the latter two genera, which I have not had an opportunity of verifying for myself, I must acknowledge my indebtedness to the thesis of my friend Dr. Brock2. 1 Sonsino, " Cellules a batonn. de cert. Cercaires," Arch. ital. Biol. vi. pp. 37-61 (1884); Thomas, " Life History of the Liver Fluke," Quart. Journ. Micr. Sci. xxiii. p. 127, pi. iii. fig. 20 (1883). 2 " Phylogenie d. dibranch. Ceph.," Morph. Jahrb. vi. 1880. |
