158 [December, 
at p. 299 he states his having observed them himself. De Geer also 
mentions and figures them, and named the insect Aphis gallarum ulmi. 
Etienne Louis GeofFroy, in his " Histoire abregee des Insectes," vol. i. 
p. 49i, (1764) refers the insect to the Aphis ulmi of Linnaeus, (Faun. 
Suec. ed. I, No. 705). Geoffroy says: "On trouve ce puceron en 
grande quantite sur I'orme ; il pique la substance des feuilles, pour 
y deposer ses oeufs, et le sue venant a s'extravaser, forme des vesicules 
souvent tres-grosses, creuses en dedans, qui tiennent a la feuille par 
un pedicule quelquefois assez etroit. Au bout de quelque tems, les 
petits pucerons eclosent dans I'interieur de cette espece de nid, et apres 
etre grossis ils font une ouverture a la vesicule, dont ils sortent." 
In 1770, Von Gleichen, in his " Versuch einer Geschichte der 
Blattlause und Blattlausfresser des Ulmenbaums," gives a long account 
of Ulmus galls. Kaltenbach extracts the most interesting remarks, 
which may be translated as follovsrs. " In the beginning of May, as 
soon as the leaves of elm have attained about half their size, they 
are already beset with innumerable little knobs. One rarely opens one 
of these knobs without finding within a small brown animal. Only in 
its slow gait does it differ from a lifeless atom. I have to thank my 
strong lens for enabling me to recognise it as a plant-louse. In the 
first week in June, the mother commences to deposit her young. At 
this time one cannot open a gall without finding from twenty to forty 
young ones deposited by the mother. Above forty I have never seen. 
The beginning of the third week in June is the customary time when 
the whole posterity of a mother plant-louse have moulted for the last 
time and are seen with wings. At this period the bladders are filled 
equally with insects and cast-skins. The state of the mother then 
strikes one as being very lamentable ; her hitherto vigorous body is 
now crumpled and shrivelled up like an empty bladder. One finds no 
hard excrement in the galls, but their inner walls look as if sprinkled 
with water, which perhaps proceeds from the wateiy nature of their 
excrement." Kaltenbach, to whose work I have referred above, 
("Monographic der Familien der Pflanzenlause, 1843-4), describes an 
insect under the name of Tetraneura ulmi, (p. 189-193), and remarks 
that the galls vary in size from that of a pea to that of a bean, which 
would also seem to apply to Gleichen's description. Kaltenbach refers 
to Geoffroy and Eeaumur, and says that he has not been able to find 
diff'erences between the inhabitants of the small and large galls, though 
the discrepancy in the sizes is very great. The galls found by me 
and Mr. Smith are certainly the same as those of the two Geoffroys, 
Eeaumur, and De Geer. I have said that the galls when found were 
