34 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
a vegetable honey- dew. The Aphides help to make the former, how or 
when the latter is exuded has never been definitely stated. 
But Biisgen’s observations lead him to conclude that all honey-dew 
— excepting sugary exudations caused by parasitic fungi — is an excretion 
of the plant-lice. In twenty-four hours an Aphis can produce from 
4—48 drops, so that a few plant-lice can form a large quantity of honey- 
dew. By experiments Biisgen has shown that the honey-dew does not 
induce any osmotic flow from the cells of the plants. 
The author then describes the nutrition of the plant-lice, the action 
of their mouth-parts, the manner in which they pierce the plants, the 
secretion which the insects exude in the act of piercing, the whole process 
of sucking up the food. He then discusses the injurious effects of the 
honey-dew upon the plants ; its presence makes it easier for fungi to 
establish themselves. On the other hand, the removal of sugar may be 
sometimes useful, as it occurs normally in nectaries, and the hcney-dew 
attracts ants, which in moderate numbers may be also useful to plants. 
The results of analysing the honey-dew are noted ; while intact leaves 
contained 4'15 parts of cane-sugar to one of inverted sugar, and no 
dextrin, the lioney-dew contained 1 • 92 parts of cane-sugar to one of 
inverted sugar and '76 of dextrin. 
The honey-dew issues from the anus of the Aphides, not from the 
dorsal tubes, as is often alleged. The dorsal tubes secrete a “ wax- 
like ” material which is protective, often saving the Aphides from their 
minute insect foes. 
Relationships of Papilionidse.* — Dr. E. Haase discusses, in a very 
elaborate way, the mimicry and systematic relationships of Papilionidas. 
Reliable results cannot be based on a study of the markings alone ; thus 
the genera Doritis and Parnassius are very nearly allied, but are quite 
different in markings. In the modification of the markings there 
is indeed a certain regularity, but even within a genus this does not 
always hold good. Among species of Papilio, the primitive form seems 
to have been yellow wuth about ten dark cross-bands on each wing. In 
Sericinus and Armandia, two genera nearly related to Papilio as regards 
venation, simple modifications of the primary marking occur in the 
fusion of adjacent bands and intervening zones. The cross striping on 
the upper surface of the wings of Doritis is also primitive, and leads on 
to spots and bands. In our limited space it is not possible for us to do 
more than notice the general tenour of this memoir, especially since 
the comparison of different forms involves an exceedingly complex 
nomenclature. 
B. Myriopoda. 
Reproduction of Diplopoda.f — Dr. 0. vom Rath points out that the 
rarity of embryological researches on Myriopods is in part due to 
ignorance in regard to their reproduction. He has therefore studied this 
in the Diplopoda, especially in the genera Polydesmus, Julus and 
Glomeris. In Diplopoda the reproductive organs lie under the gut, and 
* Bibliotheca Zoologica (Leuckart and Chun), viii. (1891) jip. 1-112, 9 figs 
(xi. (?) pis. not yet published). 
f Bar. Nat. Gesell. Freiburg i. B., v. (1890) pp. 1-28 (1 pi.). 
