WINE-MAKING IN CALIFORNIA. bi 



varieties. The change during that same year even extended 

 to France, showing that atmospheric changes could not be 

 its sole cause. 



Influence of Root Conditions. It is more probably attrib- 

 utable to the influence of the root. During the whole inves- 

 tigation there has been noticed a very decided effect upon 

 the different forms, caused undoubtedly by the nature of the 

 rtfots upon which the insects are living. In our laboratory 

 experiments the larvae are much smaller, more active or rest- 

 less, and apparently more numerous than upon roots in their 

 normal state; our specimens being, of course, drier, and in a 

 poorer condition. The wing-pad insects, in the vineyard, 

 are formed only upon the smallest and most tuberous roots, 

 and in proportionately decreasing numbers as the roots be- 

 come harder, scarcely ever appearing upon those which have 

 become tough and woody. 



Identity of the Root and Leaf Louse. Regarding the above 

 anomalous appearance of the gall-louse type, it should be 

 noticed that it has come upon a vine which has had no com- 

 munication with any outside of those with which it has been 

 associated for years, and probably has had no way of becom- 

 ing infected with any foreign type. If, as some maintain, 

 there be no direct relation between the two types, how is it 

 that the vine has borne them for a single year only, and that 

 they have not appeared again in 1885? They -came at a 

 time, too, when we know that the temporary change of the 

 nature of the root system of the vine, caused by seasonal 

 peculiarities, had materially changed the nature of the other 

 forms produced upon them. It is said that climatic changes 

 influence, to a certain extent, the type which shall predom- 

 inate. If it holds in this case, it must be through the stimu- 

 lating influence of climate on the peculiar root growth which 

 made possible the development of a large number of winged 

 insects, which may possibly have been the means through 



