M . Leuekart on the Reproduction of Bark-lice. 323 



tion of those remarkable pine-apple-like galls which, as we shall 

 see hereafter, serve as the dwelling-place of the second genera- 

 tion of our animal. 



After the Fir-louse, constantly increasing in size, has re- 

 peatedly changed its skin in the course of the next three weeks, 

 and at the same time renewed its woolly covering (Kaltenbach), 

 which, as is well known, pushes out gradually from the skin of 

 the body in single threads, as a secretion (wax ?), the oviposition 

 commences, still before the evolution of the young shoot. The 

 eggs are attached to the bud behind the mother by means of a 

 short style, and are usually also clothed at the same time with cast 

 woolly threads ; they gradually accumulate here in such quanti- 

 ties, that as many as 200 of them may not unfrequently be 

 counted* towards the close of the oviposition, which, indeed, does 

 not arrive until the death of the mother, when the oldest eggs 

 are already hatched. 



The exclusion of the young takes place in the latter half of 

 May, soon after the young shoot has broken out through the 

 enveloping scales with its axis, which is abbreviated and thick- 

 ened at its lower end. The young brood immediately quits its 

 birthplace, and moves forward in a mass, to find a new dwelling 

 between the closely approximated swelled leaves of the shortened 

 shoot. Here the young brood completes what its mother had 

 begun. Hundreds of suckers sink into the juicy leaves ; and 

 under the influence of this continual irritation the leaves close 

 up to form that globular or oval headf which we have already 

 mentioned as the dwelling-place of the second generation. An 

 amalgamation of the leaves, such as has been supposed by some, 

 does not take place, although their outer margins are closely 

 applied to each other. Tolerably spacious cell-like cavities also 

 remain between the leaves in the interior ; and each of these is 

 almost constantly inhabited by several young plant-lice, some- 

 times a dozen together. 



These animals of the second generation are more slender and 

 mobile than the individuals which have lived through the winter, 

 from which we started in our investigations ; they also appear 

 to be by no means so continually attached by the rostrum. At 

 least, on opening a cell, a number of animals living free in the 

 interior are almost always found, whilst the rest adhere to the 

 walls. These animals, like their free parents, clothe themselves 



* Kaltenbach is far below the mark when he estimates the number of 

 eggs deposited by a single mother " at thirty or more." 



f Very frequently, however, these galls are attached excentrically upou 

 the shoot, and are then, of course, less regularly rounded. Perhaps in such 

 cases the insect has not penetrated with its rostrum quite to the middle of 

 the abbreviated axis. 



21* 



