76 Cincinnati Society of Natural History. 



In Neonymplia sosyhius, according to Edwards, the lengths in the 

 respective stages are in parts of an inch, .09, .2, .36, .42 and .56. Here 

 in the first three stages the ratio of growtli is near!}- the same. In Ly- 

 ccena jjseudargiolus, Edwards gives .04, .1, .14, .25 and .36. Here also 

 the ratio only appears in the first three stages. In JSfeonympha eury- 

 tris, Edwards gives .08, .16, .24 (thus far very regular) then .44, grow- 

 ing to 1,0. In Coenonympha gemma, .18, .34, .55, an approximate reg- 

 ularity. In PJiyciodes nycteis, .06, .18, .24, .34 and .50. In most of 

 these instances very nearly the same ratio of growth is preserved 

 through the first three stages. According to Lintner, Ceratomia quad- 

 rico7'nis, when it leaves the egg, measures .2, at its first moult it has 

 doubled this length and measures .4, at the 2d .6, at the 3d one inch, 

 and in its last stage grows from 1,6 to 2.75 or even to 3.25. Accord- 

 ing to Prof. Fernald, Platysam.ia cecropia measures 15, 20, 35 and 50 

 millimeters in its several stages. 



So many of these instances and many others which might be cited, 

 show either a regular ratio in the length of the several larval stages, 

 or at least a near approach thereto, that we are tempted to think that 

 when the ratio seems to fail it does so rather because the larvae were 

 not measured at exactl}^ corresponding periods of the several stages, or 

 because the elongation or contraction of the larvce prevented the ratio 

 from appearing to be so regular as it reall}' Avas, and that it would 

 have been more evident had the measurements been taken from the 

 moulting larvae at the end of each stage. 



As to the quantity of food consumed in each stage, I have few data 

 apart from my own observations upon Lithocolletis. Count Dandolo, 

 as quoted by Rennie and Westwood {loc. cit.), states that a silk worm 

 just hatched measures 1 line in length; after its 1st moult, 4 lines; after 

 the 2d, 6 lines; after the 3d, 12 lines; after the 4th, 20 lines; and 

 grows to 40 lines before the 5th moult, when it passes into the pupa 

 state. Here is again an approximation to the regular ratio of growth 

 of the several stages; but it does not appear how long after each moult 

 the measurements were made. Dandolo gives the quantity of food con- 

 sumed b}'' the silk worm in each stage as follows: In the 1st stage, 6 lbs; 

 in the 2d, 18 lbs; in the 3d, 60 lbs; in the 4th, 180 lbs; and in the 5th, 

 1,098 lbs. Here the quantity of food consumed in each stage was 

 almost exactly three times as much as in the preceding stage, until 

 the last stage when it is six times as much. As will be seen hereafter 

 in Lithocolletis, the larvae in each stage consumes, as nearly as it can 

 be ascertained, exactly three times as much as it did in the preceding 

 staoe. 



