398 NOTES AND COMMENTS [DECEMBER 1899 
of the past in man’s present structure, he impressed us with the idea 
that we carry about with us a museum of relics, that some of our 
structures are at present in a transition-stage of function-change, and 
that some parts are even progressing. 
In a recent essay, entitled “ Senescenza filogenetica” (Livista di 
Scienze Biol. 1899, Fasc. iv. pp. 1-7), he has pointed out (1) that 
organs in process of phylogenetic regression, eg. the tips of the lungs, 
the caudal end of the spinal cord, Morgagni’s pouches in the larynx, 
and the posterior molars, have their weak spots, their loci minoris 
resistentiae, where they are peculiarly disposed to disease; (2) that 
organs and parts of organs in process of function-change, eg. the 
thyroid, the thymus, the inferior nasal muscles, and perhaps the 
tonsils, are likewise peculiarly open to attack; and (3) that progressive 
parts, such as certain muscles and bones, are strong in their progress- 
iveness, and less liable to disease than the parts in the two preceding 
categories. One cannot help wondering with another reviewer, Dr. 
W. A. Nagel, whether the last statement will hold good in regard to 
our brains, which we fondly hope are also on the line of progress. 
There appear to be two distinct ways of interpreting this 
“phylogenetic senescence.” On the one hand, we have to consider the 
immediate physiological conditions, eg. of diminished blood-supply 
and weakened innervation, which may lessen the resisting power of a 
dwindling organ. On the other hand, we have, with Weismann, to 
go further back, and consider the possibility of a germinal struggle and 
selection among the stronger and weaker determinants, and supple- 
mentary to both interpretations there is the normal action of natural 
selection. 
Studies in Plant Morphology. 
ScHuMANN of Berlin has recently published through Engelmann 
(Leipzig) a second part (pp. 207-313) of his “ Morphologische Studien.” 
The studies are of a special and somewhat abstruse character, dealing 
with flower- and leaf-arrangement and including questions of develop- 
ment, mechanical conditions and the like. They will be read with 
interest by the somewhat limited number of botanists who can 
appreciate or follow such discussions. The first (No. IIJ.) deals with 
the vexed question of the peculiar inflorescence in the Boraginaceae 
and Solanaceae, and is a criticism of a publication by Kolkwitz. The 
second (No. IV.) is an account of the branch- and floral-development 
in a commonly grown greenhouse plant, Scirpus setaceus (Isolepis 
setacea). No. V. deals with the leaf-arrangement in screw-pines, while 
No. VI., occupying two-thirds of the whole part, and entitled “The 
Shifting of Organs on Growing Shoots,” is mainly a criticism of 
Schwendener’s views on the same subject. 
