780 THE AMERICAN NATURALIST. [VoL. XXXV. 
upon by Kerr. Harrison discusses the occurrence of tails in man, 
and reports on an interesting case brought to his notice by Dr. Wat- 
son. Brush contributes notes on cervical ribs, and Walker gives 
an account of cases of hereditary anchyloses of phalangeal joints. 
The development of the pig’s intestine is described by MacCallum, 
and the structure of the gall-bladder by Sudler; of a less anatomical 
character are Halsted’s report on the effects of injecting bile into 
the pancreas, and Opie’s account of the etiology of acute hemor- 
rhagic pancreatitis. The axillary artery and its variations are 
described by Hitzrot, the blood vessels of the lymphatic glands by 
Calvert, and the anatomical origin of the lymphatics in the liver 
by Mall, who also contributes a note on the basement membranes 
of the kidney tubules. Lewis gives an account of the pectoralis 
major muscle in man, The development of the human diaphragm 
is fully described by Mall. Neurology is represented by Mellus’s 
article on the bilateral relations of the cerebral cortex, Long’s paper 
on the development of the nuclei of the pons, and F owler’s descrip- 
tion of a model of the dentate nucleus of the cerebellum. The 
development of the generative tracts in white ants is described by 
Knower, and the modification of normal menstruation by Mosher. 
The series gives substantial evidence of the great quantity and high 
quality of advanced work done in the Hopkins Hospital. P. 
The Position of the Centrosome in Resting Cells. — By a thor- 
ough study of the segmenting eggs in Ascaris, zur Strassen" has 
shown that at each resting stage the centrosome takes up 4 position 
between the nucleus and the center of the exposed surface of the 
blastomere, Ze, lies in the axis of the cell near its distal pole. 
This position is always attained, even though it involves à consider- 
able migration on the part of the centrosome. As similar oe 
tions have been figured by other authors in the segmenting €g85 
several animals, and as the centrosome in ordinary epithelium regu- 
larly occurs in this position, zur Strassen believes that the rule 
discovered by him for Ascaris may prove to be of general sies 
tion for all kinds of epithelial tissue, including the blastoderms 
eggs. These observations favor the view that epithelial cells gens 
a true polarity, but this polarity is not one which has arisen first st 
adult epithelia. As is shown by its occurrence in the early qe 
mentation stages, it is a polarity that is fairly comparable with tha 
1Zur Strassen, O. Ueber die Lage der Centrosomen in ruhenden ers 
Archiv fiir Entwickelungsmechanik der Organismen, Bd. xii (1901), PP- IM^ 
