752 PEOCEEDINGS OF THE SOCIETY. 



of preparation, and to the Mghly refractive fluid in which the object 

 is mounted. I find with a 2/3 ToUes of 65° or a 1/4 inch of 90° (made 

 twenty-five years ago by the late Andrew Eoss) the ' suckers ' can be 

 distinctly seen, although not with equal brilliancy to the performance 

 of my ToUes 1/10 immersion lens. When viewed with the latter, 

 each of the suckers appears as an actual protrusion of the lining 

 membrane of the pseudo-trachea through a corresponding forked 

 opening of the chitinous ring, and its expansion forms the leaf-like 

 process or ' sucker ' ; each of these has a longitudinal slit or fissure 

 extending from the base to the apex ; in some of the suckers, the slit 

 is seen with the margins in close contact, in others it is more or less 

 widely open, and they all, on each pseudo-trachea, communicate with 

 a central undulating channel running its whole length. 



The elasticity of the chitinous rings does not satisfactorily 

 explain the way the suckers act ; the opening and closing of the slit 

 is most likely effected by some inherent contractile power in the 

 sucker itself, which probably is under the control of the insect's will. 

 In the imbibition of fluids, capillary attraction must also play a very 

 important part, and it seems possible that the so-called ' suckers ' 

 may maintain a regulating action in this respect, and thus prevent 

 what would be an injurious, or even fatal absorption. 



I think if Dr. Anthony will examine a proboscis mounted by 

 Mr. Sharp's method, he will candidly admit that his illustrations 

 need something more than ' small alterations and corrections ' to bring 

 them ' up to date.' 



As no allusion to his paper was made by any of the members 

 present at the November meeting of the Society, the inference is, that 

 with the exception of those to whom Dr. Anthony has personally 

 shown his preparations and dissections, the ' suctorial organs ' up to 

 that time were generally unknown. 



I used the term ' endoderm ' in the same way Mr. B. T. Lowne 

 has done in his work on the ' Anatomy and Physiology of the Blow- 

 fly,' to indicate ' the innermost cuticular layer of the integument.' 



It is likely that the 'suckers' consist of the three layers of 

 the integument ; certainly, they have an outer layer of the proto- 

 derm, which Mr. Lowne describes (p. 9, ' Anatomy and Physiology 

 of the Blow-fly ') as ' transparent and continuous over the whole 

 surface of the insect, investing all the appendages and processes of 

 the skin, even the hairs, and covering the surface of the eyes. It 

 appears to be continuous with the lining membrane of the tracheal 

 system, and to extend throughout the digestive cavity, even although 

 it is somewhat modified in the latter.' 



I beg to send a slide of the blow-fly proboscis (mounted by 

 Mr. Sharp), showing the ' suctorial organs,' as a donation to the 

 Society's cabinet. 



Mr. Sharp also sends for publication his method of preparation 

 and mounting in the biniodide of mercury solution " (supra, p. 733). 



The President said Mr. Wright's communication placed the matter 

 in a somewhat different light and gave them additional information. 



Mr. Suffolk said he had examined Mr. Wright's first specimen and 



