270 Correspondence of J. Nickles. 
which disappear, or which are not produced when the _ proportion of 
water is more considerable. 
The facts may explain the observation by Th. de Saussure, t that the 
roots of plants placed in certain saline solutions absorb proportionally 
more of water than of the salts dissolved. M. Chevreul, moreover, 
dry tissue, tendons, e. g., the tube being hermetically sealed; after 
some time a orpaaliieation of the salt is seen above the level of the 
liqui ‘sid 
tion is a point deserving especial attention. This temperature varies 
for each species, and it is well to ascertain it for each separately. In 
general, for the winter fish, as — it is between 6° and 8° C. ; for the 
early spring fishes, as pike, 8° to 10°.; for the later spring, hs perch, 
14° to 16° C.; and finally for fishes of summer, as the barbel, 20° 
to 25° C. 
The necessity of a specific temperature is connected also with the 
vitality of the spermatozoids of different species, which is of short dura- 
tion, it not exceeding 8 minutes in the pike, whilst in man it lasts 8 
hours. The maximum of vitality for the spermatozoids of the pike has 
been obtained at +2° C.; a higher temperature destroys them rapidly. 
The spawn of the pike is het perfectly well in ice ee and the sper- 
matozoids perish only with ac below 1 
movements, 
M. de Quatrefages deduces some rules which are important to the 
artof pisciculture, bearing especially upon the apogee of the spawn. 
e water should not be supplied with the spawn in advance ; it is 
well to leave ets spawn in place even till the “st of employing it, 
and ms shit ore should follow soon, upon the death of the male fish. 
e the fecundation should take place within a day or twelve 
hours Bees the death of the animal, the spawn should be then taken 
and kept separate. 
. rve the spawn, it should not be placed in the water, or in 
the open air, but better in a moist linen cloth, which is kept at a tem- 
perate equal to, ora little below that, which fot each oe gives t 
cessary to detach for each, the quantity of spawn rect and leave 
the rest in some convenient place. 
Over-heated Steam applied to the Carbonizing of Wood.—For several 
years past, erenberee steam has been used in numerous industrial 
operations, e may say generally that it may be employed ae all 
