SCIENTIFIC SUMMARY. 
103 
diminishes gradually as its age increases, up towards the age of four or five 
years ; when about three it attains half the size which it is to become when 
full-grown. When from four to five years of age, the increase in size is very 
regular each year up to sixteen years, that is to say up to the age of puberty ; 
this annual increase is nearly fifty-six millimetres. After the age of puberty 
the size continues to increase, but feebly; when from sixteen to seventeen 
years old the individual increases four centimetres (*60 inch). In the two 
years following it increases only one inch. The total increase in size of man 
does not appear to be entirely terminated when he is twenty-five years old. 
The mean size is a little larger in cities than in the country.” 
Have Animals the Tower of changing their Colour according to Circum- 
stances ? — It would seem, from some recent researches of M. Pouchet, that 
they have this power. This was very well shown in some experiments he 
made on the Palcemon Serratus. The following is M. Poucliet’s descrip- 
tion : 11 Animals from three to four centimetres long are the best to 
experiment upon, placed in porcelain vessels with black or white bottoms. 
The crabs that fishermen bring ashore have a rose or a dark lily colour ; if 
they are put into vessels with black or white bottoms, in twenty-four hours 
they will assume a colour wholly unlike each other. Those in the white 
dish are yellowish, almost colourless, as if they had just shed their skin, and 
those in the dark coloured dish are of a brown red colour. When changed, 
the pale one into the dark coloured dish, and vice versa , they change colour 
in a corresponding manner. The change of a pale one to a dark colour was 
more rapid than the reverse. Under favourable conditions we can create a 
yellow, red, and blue Pakemon. If a foct is removed when any one of 
these colours is present, and put into a solution of sugar, the three colours 
appear successively before tile eye. The microscope reveals the sequel to 
this. If the pigment cells are pressed together like balls, then they are too 
minute to mirror themselves upon the retina. As soon as the animal is 
placed upon a dark ground the colouring cells are distended and send out 
little branches on all sides ; then they become perceptible to the eye. The 
animal becomes red rose coloured when nothing weakens the lively colour 
of the pigment cells. As the branches of the latter distend under the hypo- 
dermis they receive a cobalt colour, and the carmine of the pigment cells 
becomes thereby browned, and thus the Pakemon takes on a colour corre- 
sponding to the foundation. If the colouring cells contract again, the blue 
remains six or seven hours in the liypodermis, and then gradually disappears. 
With the Palsemon, as with fish, the change of colour is the result of visual 
impression.” 
Norwegian Tar in the Treatment of Wounds. — Tar, or tar water, is not a 
very novel means of treating wounds with. Still, M. Sarazin thinks it is, 
and he has presented the French Academy with a memoir on the subject. 
In this [Nov. 16, 1874] he states that he has treated several amputations [a 
list of which he gives] with Norwegian tar as an exclusive dressing, and all . 
with the best results. He gives the exact mode of dealing with the wounds, 
according as they are upon the limbs or chest, but for this we must refer our 
readers to the memoir itself. 
A new Compound in Urine has been discovered by Herr F. Baumstark. 
He has a paper in a recent number of u Liebig’s Annalen,” in which lie says 
