14 
POPULAR SCIENCE REVIEW. 
Dr. Maddox took up this much controverted scale question, 
and sent a paper to the last-named society in May 1871, ac- 
companied with a series of careful drawings given in the 
c Monthly Journal 5 for June. This paper should be referred 
to, and the drawings carefully examined, in order to appreciate 
his work. He took a great deal of pains with chemical sol- 
vents to remove oily matters, and finally made out a ribbed 
structure, to which he thought the beaded aspects were due, as 
fine ribs crossing each other would give that effect. It does 
not, however, seem that the existence of such structures as Dr. 
Maddox figures negatives the existence of deposits in a more or 
less beaded form, nor do the investigations of Mr. Wenham, 
which prove the reality of surface irregularities more or less 
corresponding with the exclamation marks. 
The reader may by this time have had enough of butterfly 
scales, and we turn to another subject, also entomological — a 
demonstration by Mr. Lowne that the so-called “ suckers ” on 
the feet of the water-beetle ( Dytiscus marginalis ) are not 
suckers at all, but an apparatus resembling the cushions 
attached to the feet of blow-flies for exuding a sticky fluid by 
w r hich the creatures can be sustained in opposition to the force 
of gravity. The cushions, or pulvilli , of the Dytiscus and other 
insects seem to have been taken for suckers without any suffi- 
cient ground for such an opinion, and when it seemed a pro- 
bable guess that they and other insects capable of strongly 
attaching themselves by their feet did so by some sort of air- 
pump mechanism. 
Mr. Lowne found the pulvillus of the Dytiscus a mere modi- 
fication of the structure of that organ as seen in common flies. 
He traced in it a secreting sac, supplying a viscous fluid, which 
percolated through u disk-bearing hairs.’ He showed that a 
dytiscus, made insensible by chloroform, mechanically adhered 
to the inner glass of the receiver of an air-pump when the air 
was exhausted, and when, if atmospheric pressure had caused 
the adhesion, it must have fallen. Common flies are frequently 
found dead and adhering to window panes, the sticky fluid 
having hardened while they were alive and rendered them pri- 
soners after their decease. Mr. Lowne has noticed in some 
dytisci a loss of tarsal disks, apparently from their having been 
allowed to adhere too tight, so that the insects had to pull their 
legs away without them. 
During the past year numerous papers have appeared relating 
to the various forms of minute life, somewhat jumbled together 
under the now popular name Infusoria , and, as usual, the 
spontaneous generation controversy has continued without ex- 
hibiting any symptoms of final settlement. Indeed, it seems 
more likely to be decided at last by reasoning from a large 
