ZOOLOGY. 175 
cavity ; and they refer to specimens made by themselves in Flour- 
ens’ laboratory, and now in the Musée Dupuytren, in confirmation 
of their theory. As regards the separation of metallic threads 
drilled into the bone, they think that in Wolff’s experiments the 
two wires passed into the shaft of the bone were too near the 
epiphysis to furnish any satisfactory result. Finally, they give the 
details of a series of experiments conducted under Flourens’ direc- 
tion, in which madder was given te young pigs up to a certain 
period, when one of the litter was Killed, and its bones prepared as 
_ objects of comparison with those of the rest, which were killed 
afterwards at stated intervals up to eighteen months. The bones 
of these animals, they declare, clearly demonstrate the correctness 
of the old doctrine, and prove irrefragably that all. increase in 
diameter is due to fresh subperiostitic deposits, whilst all increase 
in length is caused by the progressive ossification of the osteolog- 
ical elements supplied by the cartilage of conjugation between the 
diaphysis and the epiphysis. Moreover their experiments incident- 
ally showed that the long bones increase in length more at one ex- 
tremity (the upper or proximal),than at the other.—The Academy. 
Mrapow Lark wit Four Lees.—I have a Meadow lark 
(Sturnella magna), more than half grown, which possesses four 
legs. It lived about a week after capture, and for a time made 
use of all four.’ The extra or hinder pair is a little shorter than the 
front, and slenderer. One of them has all the toes well formed ; 
the other has three delicate front toes, and instead of a hind one, a 
Small appendage half way up the tarsus. Their femurs are 
attached to the end of the coccyx. This necessitated a one- 
sided Position of the tail. There are two cloacæ, one on each 
side of the rump. This proves, as Vrolik has remarked, that in 
heteradelphs there are always the rudiments of two bodies. The 
front pair of legs, the wings, and all other parts are well devel- 
oped.— James ORTON. 
Wuen 1s Sex Dererminev?— The interesting and able essay 
of Mrs. Treat that we give our readers in this number contains _ 
Some interesting facts which are supposed by her to bear on this ~ 
matter. We may, however, give some data which tend to show 
that the sex of the future insect, and probably of ‘all animals, that 
reproduce by eggs, is determined at or about the time of concep- 
_ tion or at least early i in the embryonic state. 
