ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
171 
all the points adduced are only indirect and not direct proofs. He is 
inclined, however, to regard Bacteria as the cause of the phenomenon. 
The characteristics of this luminosity appear to be, that it is not confined 
to peculiar, specially luminous species, but is found in the most common 
and widely distributed. It is not a localized luminosity, but extends 
over the entire body and all its appendages. It is entirely independent 
of the whole animal, and persists for a long time even in alcohol. No 
observer seems to have been able to detect any structures which resemble 
luminous organs, although well preserved midges have been investigated. 
As the males are luminous as much as the females, the luminosity can- 
not be of service from a sexual point of view, nor can it serve as a lure, 
for midges are not predaceous insects. 
Life-history of Chernies abietis.* — Herr N. Cholodkowsky with- 
draws his previously expressed opinion that the normal host of Chermes 
abietis L. might in the north be Pinus sylvestris and not the larch. He 
finds that the insects do not survive the winter on the fir. But more 
important is his conclusion that the species includes two distinct races 
— a yellow and a green. The yellow race is commoner in North Bussia, 
where the green race only occurs in parks and gardens. Linnaeus de- 
scribed the yellow race as Gh. abietis, Batzeburg described the green 
race as Ch. viridis. Similarly Gh. strobilobius includes two distinct races, 
one of which the author had described as Gh. lapponicus. 
Systematic Position of Siphonaptera.! — Prof. A. S. Packard has a 
critical notice of recent work on these insects, and comes to the conclusion 
that they form an order independent of the Diptera, though on the whole 
more closely allied to them than to any other order of Insects. After 
comparing their embryonic stages with those of the Diptera, he passes to 
the differences in the adult condition. Among their characteristics may 
be noted the absence of a clypeus and labrum, the homology of their 
thoracic segments, and the great development of the legs, though this, 
of course, is an adaptive character. He sums up in a few words the 
characteristics of the group, and concludes with some hints as to their 
origin. It is difficult to say whence the Diptera arose, for, owing to the 
high degree of the specialization of some of their organs and the atrophy 
of others, they diverge widely from the primitive forms of the Insecta. 
Like the Diptera, the Siphonaptera have no traces of temporary abdo- 
minal legs, and this seems to show that they are the most extremely 
modified of all insects. We must, it appears, be content to say that the 
Siphonaptera stand nearer to the Diptera than to any other order, and 
that they must have diverged from the ancestral stem before the existing 
flies had become so extremely specialized as we now find them to be. 
Information is wanted as to the presence or absence of temporary 
abdominal legs, of the imaginal discs of the wings, and of rudiments 
of wings in the pupa, as well as to the development of the labium. 
Spermatogenesis of Caloptenus femur-rubrum.J — Mr. E. Y. Wilcox 
has a preliminary notice of the spermatogenesis of this Orthopteron, the 
testicular follicles of which are long blind tubes. In the early prophases 
* Zool. Anzeig., xvii. (1894) pp. 434-7. 
f Proc. Boston Soc. Nat. Hist., xxvi. (1894) pp. 312-55 (35 figs.). 
x Anat. Anzeig., x. (1894) pp. 303 and 4. 
