SELECTED NOTES. 183 



air. Minute air-vessels do exist in very great numbers, both in 

 the thorax and abdomen. W. Jenkinson. 



I think we have never had any box that could beat this, and 

 very few that could come up to it. If there are any members who 

 (as Mr. Jenkinson thinks) can feel no interest in these slides — well, 

 so much the worse for those members ! If members generally 

 would take half the trouble that Mr. J. has taken to please and 

 instruct, and if they would (as Mr. J. has done) send out their 

 best slides, then I think the prospects of the Society would 

 rapidly improve. 



Tarsus and Pulvilli.- I am not quite sure what is meant by 

 " semi- or half- tubes " ; the tubes seem to me to be separate. I 

 do not see why the walls of the gland-cases should not be porous 

 and the viscid fluid ooze through. I consider that the suggestion 

 that the viscid fluid takes up and retains disease-germs for the 

 benefit of man wholly ifiadmissible. I believe it to be an axiom in 

 evolutionary science that no creature developes any organ or habit 

 for the benefit of any other, unless it is itself benefited by benefit- 

 ing the other, as in the case of the ants and the thorny acacia of 

 South America. 



The opinion of Mr. Newton as to the Organ of Memory in the 

 head of the Blow-fly seems very daring' and entirely unverifiable. 



Frontal Sac— I confess I do not understand the speculations 

 on the function of the frontal sac. Is it meant that when the pro- 

 boscis is protruded it is distended with air ? I should have sup- 

 posed from analogy it was more likely distended with blood. 



With regard to Mr. Jenkinson's postscript, the experiment with 

 the cricket seems to establish the theory of the efferent functions 

 of the thoracic spiracles ; but to make the proof complete it would 

 be necessary to establish a connection between the tracheae of the 

 abdominal and of the thoracic spiracles ; or might it be possible 

 that the air introduced by the afferent tracheae should be dis- 

 charged into the cavity of the body, and taken up thence by the 

 efferent tracheae to be discharged through the thoracic spiracles ? 



R. S. Pattrick. 



