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Proceedings of the Royal Society of Edinburgh. [Sess. 
The author has selected the above names for the following reasons : — 
Generation II . — He considers that the name Gallicola describes the 
outstanding feature of this generation in the family Chermesidse. The 
terms (a) mi grans and (b) non-migrans are less clumsy than ( a ) alata non- 
migrans and ( b ) migrans alata, while the words monoecious and dioecious 
have special meanings in botany. 
Generation III . — The name Colonici has been established by Burdon in 
British literature. So long as the non-Picea host is considered intermediate, 
this term may stand (see Part I\ r , Section I). Cholodkovsky has accepted 
the terms (a) sistens and ( b ) progrediens. 
3. Previous Research. 
The galls made by the Chermes species were observed before the insects 
themselves. In 1583 the Dutch botanist Clusius (30) referred to the galls, 
but it was not until the eighteenth century that it was discovered that 
insects lived within the galls. Linney (41, 42), Hartig (38, 39), Kaltenbach 
(40), and Ratzeburg (51) studied the insects. Blochmann (1) discovered 
the males in 1887, and between that time and 1889 Blochmann (2), Cholod- 
kovsky (14, 15, and 16), and Dreyfus (32, 33) independently discovered the 
regular migrations. Further, Blochmann (2) was the first to regard spruce 
as the original host of the Chermes. Dreyfus enunciated what has been 
termed the “ Parallel-row Theory.” It has been defined by Borner as 
follows : “ The Chermes not only pass through a heterogonism * in five 
separate generations, but one and the same species can live in related rows 
by the temporary suppression of the true heterogonous circles.” 
Cholodkovsky (14-29) has continued his researches to the present day. 
When Blochmann published that the intermediate host of Chermes abietis, 
L., was larch, Cholodkovsky sought to determine how this species lived in 
Northern Europe, where larch was absent. Finally, he discovered what he 
considered to be two separate species, one with a cycle of five generations 
on spruce and larch, which he named Chermes viridis, Ratz., and another 
closely resembling the above, but with a cycle of two generations on spruce 
only. He called this second species Chermes abietis, Kalt. He found the 
same for the species Chermes strobilobius, Kalt., there being a non-migrating 
species, Chermes lapponicus, with two varieties, “ prgecox ” Cholod. and 
“ tardus ” Dreyfus. We thus have the establishment of the so-called par- 
thenogenetic species, there being no sexual generation in Chermes abietis, 
* Heterogonous: producing offspring dissimilar to the parent. Heterogonism: state of 
being heterogonous. — Murray’s Dictionary. 
