130 MR. W. E. HOYLE ON THE [Mar. 5, 



Towards the margins of the pads the peculiarities of the epithelium 

 gradually disappear. The cells become shorter, their nuclei more 

 deeply stained, and they pass by insensible degrees into the flattened 

 pavement epithelium which lines the rest of the siphon. At the 

 anterior extremity of the organ it is raised up into a free process, 

 which is completely surrounded by the layer of these highly retractive 

 bodies. 



I have also examined sections of this organ in the case of Taonius 

 both young and adult, in the embryos of Ommasti-ephes, Sepia, and 

 Loligo. In its general features the minute structure of the organ 

 is the same in all these instances, but it was only in Gonatus that I was 

 able to discover the highly refracting globules described above. What 

 the relation of these may be to the fusiform rods described by 

 Midler and Boll I will not attempt to decide at present, but must 

 leave any further histological discussion till an opportunity offers 

 for describing its structure in Taonius and other forms where it is 

 highly evolved. 



I shall, however, venture a suggestion as to the function which it 

 possibly discharges, because a hypothesis, even though it may 

 eventually prove to be mistaken, affords a useful guide in subsequent 

 researches. The theories of a sensory or of a phosphorescent pur- 

 pose in this organ seem to be sufficiently negatived by its situation 

 in a closed space through which only effete products from the body 

 are discharged. Brock is, 1 think, in error when he states that the 

 main interest of this organ is that it affords an instance of the occur- 

 rence in Mollusca of nettle-cells or of bodies allied to them. To my 

 mind the resemblance to nettle-cells is purely superficial. Miiller, 

 who noted it, distinctly remarks that they have no filament, and 

 Boll, as above mentioned, did not think that they were so much like 

 nettle-cells as like the rod-bearing cells of the Turbellaria — an opinion 

 which is fully borne out by his figures. The view that the modified 

 epithelium discharges some secretion seems on the whole the most 

 feasible, and is supported by the existence of the structureless layer 

 observed on the surface of the epithelium, which, it may be remarked, 

 is of considerable thickness in the adult Taonius. The difficulty 

 hitherto has been to discover the purpose served by this secreted 

 matter. 



I would suggest that possibly this funnel- organ is an apparatus 

 for the closure of the funnel, that it is, in fact, functionally, though 

 not morphologically, a valve. 



I am led to this conclusion by the following considerations : — 



1. The fact that in a very large number of sections which I have 

 examined the pads are so disposed as to very nearly, if not quite, 

 occlude the lumen. I need only refer to the two instances figured 

 in the woodcut as examples. 



2. The fact that in those forms in which the organ is most highly 

 differentiated in the adult the valve is absent, as for example in the 

 genus Taonius. 



3. In this case the presence of a sticky or viscous secretion would 

 be of obvious utility in securing the more perfect apposition of the 



