TRANSMISSION OF MODIFICATIONS 393 



When reading of the various processes and acts in insect economy, as 

 observed and recorded in published life histories, it is quite natural to 

 suppose that these processes are fixed, absolute, and unchangeable, while 

 as matter of fact many of them are subject to modifications. Sometimes 

 these variations have apparent reason in surrounding conditions, and again 

 they can be ascribed only to individual peculiarity. . . . 



A crescent puncture is usually supposed to represent an egg or an 

 attempt at egg laying, but this does not always hold true, because, as 

 stated above, some crescent cuts are made without the accompaniment of 

 egg laying. On May 27, 1903, fallen apples, twenty-five in number, were 

 picked up at random for examination of the crescent punctures. Nearly 

 all were more or less punctured by the apple curculio, but these punctures 

 are not considered here. Two fruits bore apple-curculio punctures only, so 

 that the number examined for crescent marks was twenty-three. On these 

 twenty- three apples were fifty-eight crescent marks, or 2.52 to each apple. 

 There were also thirty-five feeding punctures made by the plum curculio. 

 Of the fifty-eight crescent cuts, fourteen, or 24.14 per cent, had no egg 

 cavities and contained no eggs. The remaining forty-four crescent cuts 

 had forty-five egg cavities. Some variation in the location of the egg 

 cavities was observed ; usually they occupied the center of the crescent, 

 but some of these were not so situated. Of the forty-five egg cavities, 

 thirty-four, or 75.56 per cent, were located at or near the center of the 

 crescent ; eleven, or 24.44 P er cent, were located near the ends of the 

 crescents. In one case there were two egg cavities within one crescent, 

 one on each side halfway between the center and tip. By another modifi- 

 cation one of the egg cavities, instead of .being excavated from the surface, 

 was excavated from the bottom at the center of a crescent cut. It was of 

 usual dimensions, extended back obliquely towards the surface, and con- 

 tained an egg. Evidently in this case the crescent was cut first and the 

 cavity excavated afterwards. . . . 



The statements we have quoted regarding the details of oviposition of 

 the plum curculio, together with the observations recorded, indicate varia- 

 tion in details sufficient to confuse the layman and even to puzzle the 

 expert if he seek to cover rightly any detail with a general statement that 

 will fit all cases. Two conclusions are open : either some individual insects 

 have faulty instincts or there is more than one acceptable way of performing 

 several of the details of oviposition. The writer accepts the latter conclusion. 



From this it is seen that the somewhat complicated process 

 of egg laying varies greatly in detail ; that the time consumed 

 varies at least from fifteen and a half to twenty-six and a half 

 minutes ; that important details are often omitted ; and that in 

 a large proportion of cases even the final object is not attained. 

 Knowing these variations, one is not surprised to learn that of 



