244 THE entomologist's reooed. 



13. — On the first appearance of the trachea. — Mr. Jeffrey 

 E.M.M., vol. xxiii.) thus writes on the first ajDpearance of the 

 tracheas in the embryo of Botys hjalinalis : — " On the tenth day, at 

 4.30-4.35 p.m., the first tracheaj came suddenly into view. As the 

 tracheae were almost invisible in some of the other larvte, I watched 

 one closely with the view of noting the cause of their appearing so 

 suddenly, and saw them injected as I suppose with air for the first time. 

 At 5.15 p.m. the filling of the trachea} commenced in the posterior 

 segments, a sort of cloud gathering at the band where it is close to the 

 head and in a line with the eye ; I saw an apparently dark flood start 

 from this spot, and creeping along with a sort of spasmodic effort, fill- 

 ing the branches in its course till it reached the head and the whole 

 tracheae became consjoicuously visible on that side of the body." 



14. — On the eakliest traces of pulsation in the embryo. — Of 

 the earliest traces of pulsation in the embryo of B. hyalinalis Mr. 

 Jeffrey {E.M.M., vol. xxii., pp. 126-7) writes :—" From the 5th to the 

 17th of last August (1885) I was engaged in watching the develojj- 

 ment of the embryo in some eggs of Botys hyalinaJis, which I had been 

 so fortunate as to secure, laid upon slips of glass, thus affording a good 

 opportunity for observing them under the microscope. The early 

 stages, interesting as they were, may be passed over here, but by the 

 1 nth being the tenth day after incubation, the young larva was well 

 formed, and most of the organs could be made out. That morning the 

 dorsal vessel became visible, and at 8 a.m. I noticed the first traces of 

 circulation in it. The pulsations at first were very faint and feeble, 

 taking place somewhat irregularly at long intervals of twenty and even 

 thirty seconds; at 2 p m., they had become more distinct, with shorter 

 intervals between each beat, and became still more accelerated by the 

 evening. At this time the beautiful ramifications of the tracheae came 

 rather suddenly into view. The oral organs were well-developed, and 

 conspicuous from their brown colour. The aasophagus also could be 

 distinctly traced, especially when, by a sucking action, a bolus of yelk- 

 granides was drawn down, and seen to pass into the alimentar}' canal, 

 which effort was continued at intervals on the 16th, till all the remain- 

 ing yelk-granules had been ingested. Then a period of rest took place 

 during part of the 17th, when a beautifully clear view of the heart 

 and its action was obtained, the pulsations being timed at 40 per 

 minute, increasing to 60 at 8 jj.m., the larva escaping from the egg at 

 8.10. Thus, it will be seen some sixty hours had elapsed from the time 

 I was first able to detect a circulatory movement in the dorsal vessel." 



15. — Hints from the embryo as to the number of abdominal 

 SEGMENTS IN THE LEPiDOPTEROus LARVA. — Considerable difference of 

 opinion exists between the older entomological authorities and those of 

 to-day as to the number of abdominal segments in the lepidoptera. 

 Packard was the first to draw attention to the fact that there were ten 

 somites in the larval abdomen, the old authors only giving nine. Jack- 

 son (Trans. Linn. Soc. Lond., 1889, p. 151) refers to the fact that 

 Kowalevski found ten somites in the embiyo of Sincrintlius pojmli, all 

 ten somites bearing feet (Mem. Acad. Imp. St. Peters., xvi., 1871, p. 53 ; 

 Taf. xii., figs. 8-10), whilst in an abstract of Tichomiroff's paper " On 

 the development of Bomhyx nwri," it is stated that he found eleven ab- 

 dominal somites in the embryo, all provided with feet exce2)t the 

 first (Najjles Jahreshertchtes, 1882, p. 142) ; Graber records that the 



