28 



BUSHBBRG CATALOGUE. 



dividuals, under certain conditions, abandon their nor- 

 mal underground habit, and form galls upon the leaves 

 of certain varieties of grape-vines, we have in a general 

 way, the natural history of the species. 



The annexed figure shows the abnormal swelling of 

 the rootlets, which follows the puncture of the root- 

 louse; they eventually rot and the lice forsake them and 

 betake themselves to fresh ones. As these decompose, 

 the lice congregate on the larger parts beyond, until 

 at last the root system literally wastes away. 



During the first year of attack there are scarcely any 

 outward manifestations of disease; only the second and 

 third year when the fibrous roots have vanished, and 

 the lice not only prevent the formation of new ones, 

 but settle on the larger roots, which also eventually 

 become disorganized and rot do the outward symp- 

 toms of the disease become manifest, in a sickly, yel- 

 lowish appearance ol the leaf, and a reduced growth of 

 cane; and the vine dies. When the vine is about dy- 

 ing, it is generally impossible to discover the cause of 

 the dath, the lice having previously left for fresh pas- 

 turage. 



As is frequently the case with injurious insects, the 

 Phylloxera shows a preference for and thrives best on 

 certain species, and even discriminates between varie- 

 ties, or what amounts to the same thing, practically, 

 some species, or varieties, resist its attacks and enjoy a 

 relative immunity from i's injuries. A knowledge of 

 the relative susceptibility of different varieties to the 

 attacks and injuries of the insect, is therefore of para- 

 mount importance . Information on this subject, based 



[TYPE RADICICOLA: , shows a healthv root; b, one on 

 which the lice are working, representing the knots and 

 swellings caused by their punctures; c, a root that has 

 been deserted by them, and where the rootlets have com- 

 menced to decay; d, d, d. show how the lice are found on 

 the larger roots ; e, female pupa, dorsal view ; g, winged 

 female, dorsal view.] 



on the researches of Prof. Riley, in addition to careful 

 observation and experiments, made during the last 

 four years by ourselves and our many correspondents 

 in France and in this country, are contained in this cat- 

 alogue, both in the "Description of Varieties'- and in 

 the notes to Dr. Engelinann's "Classification of Spe- 

 cies." (Pages 412.) 



The reasons why certain vines thus enjoy exemption 

 while others so readily succumb, cannot be fully ascer- 

 tained, but in a broad way it may be stated that there 

 is a relation between the susceptibility of the vine and 

 the character of its roots the slow-growing, more ten- 

 der-wooded and consequently tender-rooted varieties 

 succumbing the most readily. 



We see in the general resistibility of our purely na- 

 tive American vines against the Phylloxera, a remark- 

 able verification of that law which Darwin has so ably 

 established and aphoristically expressed, as " THE SUR- 

 VIVAL OF TUB FITTEST." 



Professor Riley, in explaining " Why the insect is 

 more injurious in Europe than here," says: "There 

 exists a certain harmony between the indigenous fauna 

 and flora of a country ; and our native vines are such 

 as, from their inherent peculiarities, have best with- 

 stood the attacks of the insect. The European vine, on 

 the contrary, succumbs more readily, not only because 

 of its more tender and delicate nature, but because it 

 has not been accustomed to the disease there being, 

 doubtless, a parallel between this case and the well- 

 known fact that diseases and parasites which are com- 

 paratively harmless among peoples long accustomed to 

 them, become virulent and often fatal when first intro- 

 duced among hitherto uncontaminated peoples. Then 

 the particular natural enemies of the insect which be- 

 long to its own class, and which in this country help to 

 keep it within due bounds, are lacking in Europe; and 

 it will require ?ome time before the closely allied Euro- 

 pean predaceous species will prey upon and check it 

 there to the same extent. The Phylloxera will, also, 

 all other things being equal, have an advantage in those 

 countries where the mildness and shortness of the win- 

 ter allow an increase in the annual number of its gen- 

 erations. Finally, the differences in soil and in modes 

 of culture have no insignificant bearing on the question 

 in hand. Though Phylloxera, in both types, is found 

 on our wild vines, it is very doubtful if such wild vines 

 in a state of nature are ever killed by it. With their 

 far reaching arms embracing shrub and tree, their 

 climbing habit unchecked by the pruner's knife, these 

 vines have a corresponding length and depth of root, 

 which render them less susceptible to injury from an 

 under-ground enemy. Our own method of growing 

 them on trellis approaches more nearly these natural 

 conditions than that employed in the ravaged French 

 districts, where the vines are grown in greater proxim- 

 ity and allowed to trail upon the ground, or are sup- 

 ported to a single stake." 



Again, after speaking of the large numbers of winged 

 females rising from the ground during late summer and 

 fall, he adds the following cogent reason in a recent 

 number of the New York Tribune: "The winged female 

 Phylloxera is wafted about, and will lay her eggs, or, 

 in other words, deliver herself of her progeny, wher- 

 ever she happens to settle. If this be upon the grape- 

 vine, well and good the young live and propagate, if 



