SCIENTIFIC SUMMARY. 
237 
tute a sort of areolar or spongy tissue. What is the object of this P It is a 
substitute for capillaries. At each dilatation of the ventricle, the blood 
rushes into all these irregular cavities, thus providing for the nutrition of 
the muscle ; whilst, at each contraction, it is as rapidly expelled. 
The Development of Amphioxus Icinceolcitus has been well described by 
Herr A. Kovalevsky, in a paper in the Archives des Sciences, and which is 
translated in the Annals of Natural History for January. It would be 
quite impossible to give even an abstract of his observations, they are stated 
in such a condensed manner, and consist so exclusively of facts. Our readers 
are aware how important it is to have the development of this aberrant crea- 
ture worked out, and will consult the paper for themselves. 
Spontaneous Generation . — M. Donne comes forward once more as the sup- 
porter of spontaneous generation, and the opponent of the Pasteur. He 
quoted the following experiment in support of his opinions: — I took some 
hen- eggs, and, having made a minute aperture, I introduced a needle 
previously brought to a red heat, and allowed about a third of the 
contents to escape. I filled the cavity thus produced with boiling distilled 
water, and closed the aperture hermetically with wax. The eggs were then 
left exposed to a temperature of from 17° to 24° centigrade. Five days 
subsequently, I raised the wax seal, and, having examined the contents of 
the egg, found it swarming with vibriones.” Whence, asks M. Donne, 
came the germs of the vibriones P It is impossible to suppose they were 
originally in the egg, for M. Donne has shown that in eggs which decom- 
pose spontaneously they are not present. It is equally difficult to imagine 
that they were introduced in the boiling distilled water. To us (Ed. 
P. S. R.) there appears to be this objection to the experiment: — In remov- 
ing a portion of the egg-contents, and introducing the water, there was 
nothing to prevent the introduction of the atmospheric air, and, therefore, 
of organic germs also. See Comptes Rendus , January 7. 
One of the causes of Silk-worm Disease. — On the 31st of December, M. 
Bechamp stated to the Academy that his experiments during the summer 
disclosed one of the sources of silk-worm disease. He took a number of 
worms from good healthy eggs, and divided them into two batches. One 
of these he fed with carefully dried mulberry leaves, and to the other he 
gave leaves highly charged with moisture. He found that all those of the 
batch fed with dried leaves passed through their metamorphoses; whilst 
those in the other series perished. Hence, he supposes, leaves charged with 
moisture to be one of the causes of the silk- worm disease. In those speci- 
mens fed on the undried, unprepared leaves, he found the peculiar pebrine 
corpuscles abundant. 
The Muscular Force of Insects. — M. Plateau, whose various researches on 
this subject we have already called attention to, has replied to one of the 
objections raised against his comparisons. It will be remembered that M. 
Plateau illustrated the enormous relative muscular power of the insect by 
contrasting it with the horse. This comparison was objected to on the 
ground that the horse has only four legs, while the insect has six. To this 
M. Plateau replies, that, of those six feet, only the two front and the two 
hind legs are engaged in the maximum effort of traction, the two others 
being clearly perpendicular to the direction in which the traction is exerted. 
Comptes Rendus, December 24. 
