OcTOBER 15, 1897. ] 
accept neither of the suggestions which 
have been offered. Useful individual mod- 
ifications are not directly due to the external 
forces, and are not due to the inherent con- 
stitution of the organism. 
The only remaining hypothesis is that 
which I have already mentioned—the view 
that whenever organisms react adaptively 
under external forces they do so because of 
special powers conferred on them by natural 
selection. This hypothesis will, it seems to 
me, meet and satisfactorily explain all the 
facts of the case, whether employed as a 
preparation or as asubstitute for hereditary 
variations accumulated by natural selec- 
tion. 
ASTROPHYSICAL NOTES. 
In the August number of the Astrophys- 
ical Journal Sir William and Lady Huggins 
publish a paper, read before the Royal So- 
ciety in June, which throws light upon the 
perplexing behavior of the H and K lines 
of calcium in solar and stellar phenomena. 
It was early noted by Young that these 
lines were especially conspicuous in the spec- 
trum of the solar chromosphere and promi- 
nences, while other calcium lines, strong in 
the ordinary solar spectrum, were seldom 
seen as bright lines. Recent researches 
with the aid of photography, chiefly by 
Hale, have still more emphasized the sig- 
nificant part played by these two radiations 
in chromosphere, prominences- and facule. 
They rival those of hydrogen and helium 
in their prevalence and in the high eleva- 
tions in the solar atmosphere in which they 
occur. It has therefore been the thought 
of many that possibly they are not due to 
calcium after all, but to some lighter gase- 
ous element, existing as an undetected im- 
purity in calcium, a view which after the 
discovery of argon in nitrogen would ap- 
pear as not wholly unreasonable. Others 
have agreed with the opinion of Lockyer 
SCIENCE. 
587 
that at the excessive solar temperature 
the spectrum of calcium would become 
simplified so as to consist of but few lines, 
chiefly H and K, perhaps due to ‘ dissocia- 
tion.’ 
The Huggins experiments now indicate, 
however, that the density is the determin- 
ing factor, and they have succeeded in pho- 
tographing in the laboratory a spectrum of 
calcium consisting solely of the H and K 
lines, with perhaps an analogous pair in 
the far ultra-violet region. This important 
result had hitherto not been accomplished 
by other investigators (although in retro- 
spect, perhaps, it will appear that such 
plates have accidentally been secured), 
chiefly because the effort has been to use 
a spark of as high intensity as possible. 
The procedure now adopted consisted in 
taking the spectrum of a spark of feeble 
intensity passing between platinum elec- 
trodes which had been moistened with a 
solution of calcic chloride. Several Ca 
lines were present, but relatively to H and 
K the other lines were less intense than 
when electrodes of metallic calcium had 
been employed. On reducing the amount 
of calcium vapor present in the spark by 
successive washings of the electrodes in 
pure water the other lines retired, finally 
leaving only H and K. 
These new results are confirmatory of 
the present view as to the extreme rareness 
of the vapors in the upper chromosphere, 
and may prove of much value in giving a 
criterion of the density of stellar atmos- 
pheres in the spectra of which the calcium 
lines appear in some of their different 
phases. 
Ty connection with the approaching dedi- 
cation of the Yerkes Observatory, which 
will oceur on October 21st and 22d, a series 
of conferences will be held (from October 
18th to 21st) which promise to be of much 
interest to astrophysicists. An extensive 
