1890,] Zoology. 581 
only the refractory and therefore worthless species will not acknowledge 
him as master when he treats them like King. 
There is therefore a strong argument in favor of the view that culti- 
vated varieties should remain intact indefinitely if conditions for growth 
remain constantly favorable.—Byron D. HALSTED, Rutgers College. 
The Causes of Cypress Knees.—From the teleological stand- 
point the the buttress function of the cypress knees was ably advanced 
in the last number of the AMERICAN NATURALIST, and while reading the 
article it occurred to me that the swaying of the trunk by winds would 
unavoidably produce a pulling strain upon roots at any angle with the 
tree, with a tendency to the elongation of such roots, particularly the 
outermost ones, and with the rebound or push of the tree in the opposite 
direction there would occur angularities at the points of greatest stress, 
in such outer roots, with sap exudation at such angles, and the piling up 
of indurated tissue in such forms as we find in the ‘‘knees.’’ Recollecting 
that Herbert Spencer had dealt with plant morphology in a general 
way, Ilooked up the reference, and believe that his Chapter II., Part V., 
Vol. II., Principles of Biology, covers the subject admirably, especially 
in the words of Sec. 279: ‘* Many commonplace facts indicate that 
the mechanical strains to which upright gravity plants are exposed, 
themselves cause increase of the dense deposits by which such plants 
are enabled to resist such’strains.’’—S, V. CLEVENGER, Chicago. 
È 
ZOOLOGY. 
Phymosoma.—A, E. Shipley has recently published his complete 
paper! on the anatomy of the West Indian gephyrean Phymosoma 
varians. Above the mouth is the horseshoe-shaped lophophore, ipm 
bears a varying number (but always even) of tentacles; below 
vascular lower lip. Both lip and lophophore have a skeleton which 
gives attachment to the retractor muscles. The nervous system con- 
sists of a bilobed brain connected with the ectoderm within the lopho- 
phore, This gives rise to three pairs of nerves, one supplying the pig- 
mented tissue of the region in front of the mouth, the second sending 
branches to the tentacles, while the third, sending a branch on either 
side of the cesophagus, unites below in the ventral nerve cord, which 
shows no traces of double origin, and which is not ganglionated. 
From it arises at intervals a single median nerve, which later divides 
1 Quarterly Jour. Micros Sci., XXXI., p. 1, Apr., 1890. 
Am. No june 6. 
