156 PROGRESS OF MICROSCOPICAL SCIENCE. 
the red glands on the upper surface of the lamina greenish, and pre- 
cipitates, in the cells containing starch, a fine-grained substance. 
And if the ammonia is neutralized by acetic acid the red colour of 
the glands is re-established, and the granules in the cells are dis- 
solved and disappear. Adding potassium again removes the colour 
and causes the starch-granules to swell up and become transparent. 
Finally, the green granules are again precipitated. After carefully 
washing out the potassium, and then treating the tissue with iodine 
(as iodide of potassium), the cells are uniformly coloured blue or 
violet. Dr. Fraustadt also found that the cells of those leaves which 
had caught little animals, or had been fed with albumen, contained 
no starch, or very much less than those which had access to no 
organic food, after these substances had been enclosed a few days. 
When dyed albumen was presented to the plant, the colour was 
absorbed even into the vascular bundle of the midrib. 
On the Eyes of Worms.— A paper of some interest is that of 
M. J. Chatin, which was presented to the French Academy (December 
18) by M. Milne Edwards. In a previous paper—of which we 
have given an abstract—the author described pretty fully the minute 
structure of the bdtonnets of crustacea. In the present paper he in- 
dicates a series of analogies between the eyes of the annelids and 
those of crustacea. The eyes of worms present three distinct types: 
(1) In Torrea the eye is extremely perfect, and comprises all the 
parts that one sees in the eye of Vertebrates. (2) In the various 
Serpule the eye is formed by one or more refractive parts placed 
in a generally elongated matrix. (3) In the Polyophthalmie the 
organ consists of one or more analogous pieces, but they are sur- 
rounded by a pigmentary mass whose limits are undecided. Now 
M. Chatin finds that the second group, that of the Serpule, presents a 
marked resemblance between its eyes and those of crustacea. Some 
genera, as, for instance, Psygmobranchus, show the analogy very 
distinctly. Their eyes are, in fact, formed by a piece in which it is 
easy to recognize two parts: one superior, refractive, corresponding to 
the crystalline lens of authors ; the other inferior, elongated, coloured 
reddish orange (P. protensus), and thinning out toward its initial 
end. If now we compare this with the arrangement in certain of the 
lower crustacea (Epimeria), we easily recognize the complete analogy 
between the crystalline lens and the cone, and between the bdtonnet 
properly so called, and the lower part brilliantly decorated as above. 
The author gives several other instances which support his views. 
Examination of the Air—The French Government has set about a 
thorough examination of the air of Paris by the Meteorological Depart- 
ment. This investigation began on the 1st of January, 1877; and it 
is described by M. Marié-Davy, in the ‘Comptes Rendus,’* somewhat in 
advance. He states that the reason of this was to seek out if he could 
discover the cause of an epidemic which has raged for some time in 
their various barracks. Especially was this the case in the barrack of 
Prince Eugene, which the War Department at last evacuated. On 
* December 27, 1876. 
