PROTOZOA. 
789 
I. Infusoria. 
Spontaneous Generation . — We give a brief resume of tlie 
diseussion in the Frencli Academy on this subject. The follow- 
ing are the conclusions of M. Coste (/. c.) : — 
I, Ciliated Infusoria make their appearance in an infusion before the for- 
mation of the so-called stroma or prolifer ot(s membrane. II. They are in- 
troduced in the form of eggs or cysts Avith the hay or moss Avith Avhich the 
infusion is made. III. Although the stroma is produced in infusions made 
Avith substances Avliich have not been in contact with the air, such as the 
pulp of apples or other fruits, yet such an infusion, if covered by a piece 
of glass, Avill not produce ciliated Infusoria; but if into such an infusion a 
single indiAudual of such genera as Kolpoda, Chilodcm, &c., be introduced, it 
Avill increase to an amazing amount. IV. The rapid increase of such In- 
fusoria is owing to their multiplication by division. V. Some of them, as 
Paramecium, Chilodon, divide Avithout becoming encysted ; others, as Kol- 
jioda, become encysted before dividing. VI. After multiplying, by division, 
in the interior of the cyst, the Kolpoda become again encysted, and remain 
in this state cA^eii during complete desiccation of the infusion ; but on being 
again moistened they return once more to active life. VII. Filters can, and 
do, let Infusoria of small size pass through them, as avcII as their ova and cysts. 
The author concludes by stating that he neither Avishes or desires to discourage 
the partisans of spontaneous generation, believing, as he does, that those 
who aflirm and those who deny its existence have both but one object 
in vicAv, viz. to elicite truth. In the discussion which followed on the 
reading of this pnper. Prof. Milne- Ed AA^ards referred to the results obtained 
by Doyere (results confirmed by a Committee of the Academy), that Tardi- 
grades, as well as many Infusoria, on being properly dried, can support a 
temperature of more than 212° F. Avithout losing the faculty of regaining ac- 
tive life on obtaining a certain quantity of fluid. M. Chevreul reminded the 
Acadeni}^ of his investigation of a kindred subject, conducted so long ago as 
1821, Avhich led him to the folloAving conclusions : — I. That if an animal 
whose fluids are coagulablo by a temperature of 194° to 201° F. is exposed to 
such a temperature in a living condition it will undoubtedly perish. II. That 
if the same animal be slowly dried by a temperature insufficient to coagulate 
or disorganize its fluids, it will, after desiccation, return to life. III. That 
an animal so dried can be exposed to such high degrees of heat as would 
otherwise have killed it. 
M. Poiichet sums up his answer to M. Coste as follows : — I. That if ci- 
liated Infusoria are by accident introduced into the infusions, they do not 
play anj'^ part in the production of heterogenesis. II. That these very In- 
fusoria are destroyed by the first phenomena of fermentation. III. That 
the pellicle formed on the surface of the maceration is a true “proli- 
ferous stroma ” for ciliated Infusoria. IV. That whenever this stroma is 
destroyed or removed, ciliated Infusoria are neAer observed. V. That 
neither the ciliated Infusoria Avhich formed the subject of these investigations, 
nor their eggs, nor their cysts, can pass through the filters. VI. That multi- 
plication by division is very far from being able to account for the extremely 
rapid development of these Infusoria. In reference to the desiccation of the 
Tardigiades, he obseiwes, in answer to Prof. Milne-Edwards, that, far from 
