20$ 



Messrs. A. Dowries and T. P. Blunt on [Dec, 19, 



essential to life as we know it, and matter, in the absence of which, 

 life has not yet been proved to exist, here unite for its destruction. 



The organisms (Bacteria) on which we have mainly experimented, 

 in their ordinary conditions of structure and development, afford an 

 example of protoplasm in a simple and uncomplicated form, but it 

 would be unreasonable to suppose that this protoplasm is so essentially 

 different in its fundamental constitution from all other protoplasm 

 that here, and here only, is this special effect of light to be found. 

 There are. indeed, many facts which prove the contrary, and indicate 

 that we are dealing, not with a special and fortuitous phenomenon, 

 but with a general law. 



But protoplasm may be very differently circumstanced in its 

 relations both to light and oxygen, it may be protected. Such pro- 

 tection may be afforded by : — 



1. Thickened, or opaque, cell- walls or envelopes. 



2. Special colouring matters, which filter out the more injurious 

 rays. 



3. Aggregation of cells, whether free or combined into tissue, the 

 inner being protected by the external. 



4. Relation of the protoplasm itself to oxygen. 



The first three are sufficiently obvious, but. as regards the last- 

 named condition of protection, a few words of explanation are 

 necessary. 



Protoplasm in its relation to oxygen varies widely. In the vast 

 majority of cases, oxygen in its free gaseous state, appears to be 

 absolutely essential for the development and reproduction of proto- 

 plasmic life, but the labours of Pasteur have sufficiently demonstrated 

 the power of some organisms, living in absence of free oxygen, to take 

 it froni certain of its combinations. During the present summer we 

 have been continually troubled in our investigation by the fact, that 

 either our materials, or the air in which we worked, had become in- 

 fected with a species of small ToruJa. Solutions exposed to sunlight 

 would remain clear for a few days — their incased companions in the 

 meantime becoming turbid with ordinary Bacteria — but slowly and 

 gradually a deposit would form at the bottom of the solution, which, 

 on examination, would prove to be the Torida in question. 



Now. if we consider the rapidity with which Torida removes dis- 

 solved oxygen from water,* and the comparative slowness with which 



a considerable period by insolation. This fact, as well as others, shows, by the way. 

 that the action does not depend on ozone formed, as G-orup v. Besanez believes 

 (■"Ann. Chem. Pharrn.." clxi. 232) is invariably the case when water evaporates. 

 We have, we may observe, never been able to detect the formation of active oxygen 

 as ozone, or peroxide of hydrogen, in cultivation solutions or in water exposed to 

 sunlight. 



* Schutzenberger, " Fermentation." pp. 107 and 13-1. 



