MR. LUBBOCK ON THE THYSANURA. 443 



freshly killed insects glitters like threads of quicksilver ; and however absurd it may 

 sound, I consider the inside of an insect, with its beautiful and rich tracery of glittering 

 tubules, to be one of the loveliest objects in nature. In searching, therefore, for 

 tracheae we are very much assisted by the presence of the air ; and while in preserved 

 specimens these organs are not easy to trace, at least towards their extremities, in fresh 

 specimens they are generally very conspicuous. 



I have not yet discovered in Papirms any other organs of respiration ; but, considering 

 how soon these animals dry up if placed in a dry atmosphere, it seems quite possible 

 that they may respire through the general surface of the skin. 



Female Generative Organs. — The ovaries of Smyntlmrus are very simple. From the 

 delicacy of their membranous envelope, it is not very easy to extract them entire ; but 

 the best way is to make a section of the animal from the back at the anterior part of 

 the cephalothorax, to the base of the spring : in this case, the ovaries will generally be 

 found uninjured, and may be separated from the other organs without very much diffi- 

 culty. They consist of a single, short and broad egg-tube on each side, and unite 

 posteriorly to form a narrow vagina about -003125" in length. Having found it impossible 

 to remove the skin in such a manner as to expose the ovaries in situ, and as the method 

 above described destroys, of course, the natural position of the organs, I am unable 

 to say much as to the usual position of the ovaries. They did not appear, however, 

 to pass directly forwards, but seemed rather to curve round from the point of attach- 

 ment to the vagina so as to lie rather in the posterior part of the body. They were, I 

 think, on the dorsal side of the intestinal canal ; but this point I unfortunately forgot 

 to note at the time. 



M. Nicolet was unsuccessful in his search for the organs of generation. " Je I'ai deja 

 dit," he says, " les difficultes que I'estreme petitesse de ces insectes oppose a la dissection, 

 rendant fort difficile I'etude de leur organisation interiem-e, qui peut-etre restera encore 

 longtemps inconnue; le hasard seul, en rendant un observateur temoin d'un accouple- 

 ment, pourra faire decouvrir leurs organes genitalis, mais un pareil hasard est difficile a 

 prevoir." I quote this sentence as an excuse for the numerous details, in the anatomy 

 of SmyntJmriis, which I have left unascertained ; many of which, however, want of time 

 alone has prevented me from making out. I may add that the small size of Smynthurus 

 gave me less difficulty than its curious form and the extreme delicacy of its internal 

 organs. By opening the animal, however, as above mentioned, I was able several 

 times to make out the vagina above described, and also to trace it to the vulva, which, 

 with the anus, opens into a common cloaca at the posterior end of the body; this, 

 however, from the great development of the segment bearing the spring, is thrown 

 apparently on to the dorsal surface. 



The only accessory organs which I could find were two small, glandular, rounded bodies 

 attached to the vagina close to its orifice. They were -0055" in width, and shaped like a 

 kidney, with the convex side in front. On the other side of each, that is to say near the 

 vulva, is a dark-brown rounded mass, about -003" in diameter. Beyond their relative 

 position, I did not make out the relation which these organs bore to one another or 

 to the vagina. 



