PHYSIOLOGY. 
457 
tains spores, their number increases, their threads break up, some 
of them become free—in a word, the culture continues its evolu¬ 
tion. This, however, proceeds more slowly, and in the same 
manner as when placed in media of less favorable nutritive 
quality. And in that case, the fragments of the bacilli often col¬ 
lect together in irregular masses, in which the spores form them 
selves, as in a kind of zooglia. 
Second .—As to the vegetability of the mycelium more or less 
sporulated, the development of which has takeu place in the dark 
chamber, it is destroyed only after 29 or 30 hours of exposure to 
a July sun, by a temperature varying between -J- 30° and + 36°. 
It is understood that the vegetability diminishes by degrees, 
before it disappears entirely. If, after four, eight, fifteen or 
twenty hours of exposure to the sun, a drop of culture is trans¬ 
ferred into others, it will be observed that the cultures of the 
second generation become less and less cloudy, in proportion to 
the period of time during which they have been exposed to the 
sun. And besides this, the appearance of the growth will take 
place more slowly. In bouillons at the temperature of our oven, 
a normal cultivation will present indications of growth after 10 
or 12 hours; while another, exposed to the sun for from four to 
eight hours, will give no evident signs of vegetation before 20 or 
24 hours; and if the culture had been exposed to the sun for .15 
to 20 hours before, 36 or 40 hours will be required. It is worthy 
of remark that cultures which proceed from another already 
exposed to the sun are less resistant to insolation than those 
which come from a normal culture. For example, it is sufficient 
to expose to the sun, for nine or ten hours, a culture whose origin 
has been similarly exposed for 25 hours, to completely destroy its 
vegetability. A culture of the third generation, whose mother 
cultures have been so exposed, first for 17, and then for nine 
hours, has quite lost its power of fecundation after an insolation 
of 10 hours. If, however, an addition is made of the sums total 
of the hours of insolation, it is observed that the loss of vegeta¬ 
bility takes place, in the average, after 27 hours. This well 
proves the clearness and gradation of the effects of insolation 
upon cultures of bacillus anthraeis. 
