15 4- Zoology. 



very recently felled healthy trees, which, though not a usual practice, he 

 has sometimes occasion to do, he has never found any of these larvae. 



3. Wounds made in a healthy tree, equal to those made by the pregnant 

 Scolyti eating their way in to deposit their eggs, will be healed in a single 

 summer; and as the Scolyti perforate in June or July, when the sap, 

 doubtless, is in full circulation, I have scarce a doubt that these perfora- 

 tions would be filled up as fast as they would be made, and the insects 

 themselves drowned for their temerity. 



4. Supposing it possible for a healthy tree to be suddenly killed by the 

 perforations of these little insects, that tree would, as a last effort, emit 

 from its roots numerous suckers or shoots; and this process would be 

 effected with such a vigour and tenaciousness of life, as to defy even the 

 pebbly pavement of Catherine Hall grove to resist it : but no such emission 

 of suckers has appeared. 



These considerations lead me to exonerate the Scolytus destructor of 

 the heavy charge you prefer against it ; and to assume that it is guiltless not 

 only of the death of the Catherine Hall trees, but also of every other tree. 



The death and disease of the Catherine Hall trees I impute to their 

 insulated condition. The grove is bounded along one side by the founda- 

 tion of a wall, and a paved walk beyond this wall ; at each end by the 

 foundations of houses ; and by the flag and pebble pavement of the public 

 street on the remaining side ; and further by a pebble pavement all over 

 the surface of the grove between the trees themselves. So that, besides 

 the confinement, and possibly drought, inflicted on their roots, a perpetual 

 trampling is induced over them, and the cheering influence of the sun's 

 rays almost totally excluded from them. 



As to the prevalence of the Scolytus in these trees, I consider it but as 

 one instance, in addition to many others already known (and multitudes 

 have yet to be discovered), of an economy surpassing admiration which 

 obtains in nature, and while it admits the disorganisation of beings, provides 

 at the same time for their transmuted reorganisation, through the interven- 

 tion of appropriate agents. Putrescent flesh (thfi xl«composing organs of 

 animals), by the intervention of carnivorous animals and insects, is again 

 animated, again modified into organs, form, and consciousness. So, in the 

 next lower world of nature, 



" See dying vegetables life sustain," 



as the dying elms sustain the Scolytus ; and the revivification of dying elms 

 through the agency of the Scolytus I take to be analogous to the reorgan- 

 isation of animal remains by the agency of the flesh fly. 



On my belief in this view I assume that whatever elm or other tree is 

 found to be attacked by Scolyti will exhibit proofs of having been fatally 

 diseased, either wholly or in the part attacked, previously to the date of 

 their attack. That appearances are against this assumption 1 readily admit, 

 but on close research they will be found to be appearances only. Healthy 

 trees felled in winter will, not unfrequently, through the resources of sap 

 and vitality contained in their vessels, emit from their bark, through the 

 spring and summer succeeding, buds and leaves, and even feeble twigs. 

 In like manner, standing trees, although affected with a disease so mortal, 

 that 



" No medicine in the world can do them good," 



will not unfrequently exhibit verdure and other signs of life and vegetation 

 for a season or two before they actually expire. We even occasionally 

 witness instances of trees growing freely in one limb while dying in an- 

 other. It is these dying branches or dying trees that are the peculiar food 

 of the larvae of the Scolytus, and therefore the nidi into which the prescient 

 mother takes care to insert her eggs, that, when her offspring shall awake 



