SCIENTIFIC SUMMARY. 
199 
on June 28, but will be too low for favourable observation. Mars is tbe 
planet of tbe quarter. He was in opposition on March 19, and will continue 
for several weeks favourably placed, both as respects distance and altitude. 
His northern hemisphere is now considerably bowed towards us and towards 
the sun ; and as this hemisphere has been less completely studied than the 
southern, observers who have good telescopes would be doing good service 
in studying the planet. Although the oppositions which occur when Mars 
is, as now, near his aphelion, are less favourable as respects distance, the 
planet is more favourably situated as respects altitude. Venus is coming- 
round into a better position for observation, and towards the end of the 
quarter will be nearly at her brightest. It is satisfactory to know that as- 
tronomers propose to study her with special care during the approaching 
months ; so that perhaps some of the perplexing questions which have been 
suggested by her spots, rotation period, inclination, &c. may be satisfactorily 
dealt with. 
BOTANY AND VEGETABLE PHYSIOLOGY. 
Experiments on the Influence of Manures on Plants. — Some very important 
experiments in this most interesting direction have been carried out by Dr. 
Masters, F.R.S., and Dr. Gilbert, F.R.S., and reported upon to the Horticul- 
tural Society, which caused them to be undertaken. The experiments were, 
as might be imagined, partly failures, for it is natural that mistakes should be 
made at the first ; but they are of special interest nevertheless, and we have 
no doubt that from the next ones we shall have much valuable matter 
to learn. One of the tables furnished by the reporters shows us that the 
grasses removed from 05 to P23 oz., or an average of about 0-8 oz., of 
mineral matter from the unmanured soil ; whilst under the same conditions 
the Leguminosce removed from under 1 to over 2 oz. ; the Achillea 3£, and 
the Plantago nearly 3^ ozs. Some idea of the richness of the soil in avail- 
able mineral matter which these amounts indicate will be acquired when it 
is stated that 1 oz. of mineral matter removed from one of the boxes by one 
of the grasses would correspond to as much per acre as would be contained 
in about 5 tons of meadow hay, 1 oz. in one of the clovers to as much per 
acre as would be removed in about 4 tons of clover hay, and 3 to 3^ ozs., as 
in the cases of the Achillea and Plantago , to a ton or more of mineral matter 
per acre. Of phosphoric acid , the grasses would, on the average, thus remove 
from the unmanured soil about one-seventh as much as was supplied where 
the heavy mineral manure was employed ; and of potass from one-fourth 
to one-third as much as the mineral manure supplied. Of phosphoric acid , 
the clovers would remove considerably more than, and of potass about as 
much as, the average of the grasses. Of both constituents the lotus would 
remove more still, and the Achillea and Plantago probably very much more. 
With nitrogenous, but without mineral manure, the amounts removed were, 
as a rule, with all the plants much greater than — in fact, in some cases once 
and a half as much as — without manure. With regard to mineral constituents , 
therefore, it may be concluded that the unmanured soils were so far drawn 
upon by the first year’s growth as to widen considerably the difference 
