May 2, 1884.] 
all his previous ones, and gave evidence of a time 
approaching when the shapes of nebulae, and the rela- 
tive brightness of the different parts, will be recorded 
photographically in a better manner than by the most 
eareful hand-drawings. The behavior of the very 
faint stars in the nebula also led to results of the 
greatest interest. These stars appear on his nega- 
tives taken with exposures of from thirty-seven to 
sixty minutes; and, as the time of exposure can be 
easily extended to hours, Mr. Common thinks it 
quite possible to get stars invisible to the eye in the 
same telescope used for photography. Mr. Common 
has already experimented with the longer exposures, 
and more details are brought out with every increase 
of the time; and it appears that the extreme limit of 
useful exposure has not even been reached at an hour 
and thirty minutes. 
Mr. Common has also obtained beautiful photo- 
graphs of other nebulae and of the planets Jupiter 
and Saturn, and has also applied himself successfully 
to obtaining photographic star-maps to stars of the 
eleventh magnitude. 
In connection with all this variety of valuable 
astronomical work, it should be noted that Mr. Com- 
mon belongs properly to the ranks of amateur as- 
tronomers; and this fact was dwelt upon at some 
length by Mr. Stone, at the conclusion of his address, 
as follows: — 
**The lesson taught is not a new one. The records of our 
society are rich in the labors of our amateur astronomers. The 
amateur who can provide himself with sufficient instrumental 
means for original research need fear no professional rivalry. 
Untrammelled by the necessity of continuing observations whose 
value largely depends on their continuity, having the power of 
taking up any subject he pleases, without fear or responsibility 
of charges of wasted time and wasted means, he possesses ad- 
vantages which are priceless in the tentative and experimental 
stages of any work. 
“It is in work of this class that the most striking advantages 
in our science must be expected ; and such work will most cer- 
tainly repay, by the gratification of personal success, the efforts 
of those who devote themselves to original work in our science; 
and the field of research presented is absolutely boundless.” 
INSECTS AND FERMENTATION. 
THANKS to a long lirre of investigators and experi- 
menters, beginning with Sprengel, and including 
among its recent leaders Darwin and Hermann 
Miller, we know that very intricate relations exist 
between flowering plants and insects which result 
to the advantage of both; many insects obtaining 
their food exclusively, or in large part, from the 
nectar and pollen of flowers, which are strengthened 
by intercrossing as a result of their visits. Within 
the last few years the activity of insects has also 
been shown to have a close connection with the dis- 
tribution of other and lower organisms. The fetid 
slime of phalloids has long been known to be attrac- 
tive to many flies and scavenger-beetles; and, as 
Mr. Gerard suggests in the case of the common 
stinkhorn (Phallus impudicus), the dissemination 
of these fungi is largely traceable to such insects. 
Rathay has likewise shown that a partnership of a 
SCIENCE. 
545 
somewhat similar nature probably exists between 
some of the rust fungi (Roestelia, Aecidium), and 
insects which feed upon the sweet secretion that 
accompanies their spermatia. In these cases the 
arrangement appears to be mutually beneficial. In 
the last it may also favor the spread of diseases of 
the higher plants, and so lead to important indirect 
results. Zymotic diseases of man and the domes- 
ticated animals are also known to be carried by the 
same active agents, which, however, appear to be 
rather accidental than specially provided for; while, 
in the asserted intervention of mosquitoes in the 
parasitism of Filaria, they are decidedly losers by 
their part in the transaction. 
Boutroux has recently shown! that insects also 
play a very important, if indirect, rdle in the life-his- 
tory of yeasts. It has been generally asserted that 
the agents of spontaneous fruit-fermentations, like 
those employed in the manufacture of wine and cider, 
are found on the surface of the ripe fruit, whence 
they readily reach the expressed juice. Boutroux 
was led to investigate their occurrence not only on 
ripe fruits, but on those which were immature, as 
well as in the saccharine secretions of flowers and 
on the bodies of the insects which visit both classes 
of objects. He prepared tubes of sterilized cherry- 
juice, or other fermentable liquid, from which germs 
were excluded by means of cotton. After these had 
shown their freedom from yeast by remaining un- 
changed for a fortnight, at a temperature favorable 
for fermentation, a fruit, flower, or insect was intro- 
duced into each, precautions being taken to prevent 
the introduction of germs from other sources. Re- 
peated transfers were made from these first propa- 
gation cultures, where several species were usually 
found, until these were isolated, when their form and 
physiological characters were studied. 
Contrary to the prevalent opinion, it was found 
that ripe fruits, as long as they are intact, bear com- 
paratively few yeast-germs, these being much more 
frequent on green fruit, as well as in the nectar of 
flowers and on the bodies of the insects which are 
common about flowers. From what appears to have 
been a careful series of experiments, Boutroux ad- 
vances the opinion that these spontaneous yeasts are 
regular inhabitants of nectar, being carried from 
flower to flower by insects in their visits for this 
beverage. After the fading of the flower, especially 
where some of its organs persist on the ripening fruit, 
they remain, the number of germs suffering constant 
diminution from rain and other causes. When the 
fruit has ripened, a few of these germs may still be 
present; while others are brought from later flowers, 
or from injured and fermenting fruit, by insects which 
feed upon the juices of the latter. The hibernation 
of these species is thought to occur on the remains 
of fallen fruit, as well as in the ground, whence 
a new supply is obtained the next spring. It is in- 
teresting to note that the species which have been 
obtained in these cultures are not identical with the 
wine and cider ferments, although some of them re- 
semble these'closely; and it is suggested, that, while 
1 Ann. des sci. naturelles, Bot., 6 sév., v., xvii., p. 144. 
