W. H. FURLONGE ON THE TULEX IRRITANS. 25 



the sheath of the penis then takes place, wliich next passes into 

 the vaginal orifice. 



I have repeatedly witnessed the copula of the insects, and though 

 I have before referred to the pulex as an animal in which the 

 typical structures and functions of the organs of insects can be 

 studied under singularly favourable circumstances, I may here re- 

 mark that in no description of investigation are these exceptional 

 advantages so great as in the study of the reproductive process. 

 When young and transparent specimens of the insect are selected 

 this important process can be seen with remarkable clearness, and 

 the animals being so closely locked together may be manipulated 

 with great facility. Even when placed between the glasses of the 

 compressor they will endure an amount of compression quite suffi- 

 cient to render the abdomen of each insect perfectly transparent 

 without the interruption of the copula. When thus examined the 

 extremity of the sheath of the penis may be seen to be continually 

 opening out and closing up, and by this action the spinous processes 

 attached to the extremity of the sheath appear, as it were, to grasp 

 the ovarian clusters I have described ; but I have not been able to 

 observe the protrusion of the penis itself during the copula, nor at 

 any time to distinguish spermatozoa in the female. 



I would strongly urge that the members of the Club should re- 

 peat these observations, when pr.obably much more than I have been 

 able to make out would be discovered in this important department 

 of insect physiology. It is by no means a difficult matter to in- 

 duce copula in the pulex. Tn general it suffices to keep the male 

 and female in separate tubes for a day or two, then to feed them, and 

 afterwards to put them together. In most cases copula immediately 

 ensues. Easy as it is, however, to make the observation, I have 

 never yet met with any microscopist who has witnessed it, with the 

 exception of one fellow worker, Mr. Mclntire, whose obBervations 

 on the subject exactly confirmed my own. If he should happen 

 to be present at the reading of this paper he will, perhaps, 

 give the Club the benefit of his observations upon the subject. 



I had intended to have closed my paper with a description of the 

 development of the Qgg through its transformations into the per- 

 fect insect, but I fear I have already trespassed upon the patience of 

 the Club too much ; I hope at a future period, however, to read a 

 short communication on this concluding portion of the life-history 

 of the Pulex Irritans. 



