8o BACTERIA IN DAILY LIFE 



changes in the physiological character of certain 

 micro-organisms. 



Dr. Lohmann, of Rostock, discovered that some 

 hours' exposure to bright sunshine entirely destroys 

 yeast cells, whilst even feeble and intermittent sun- 

 shine is capable of paralysing them, and that they 

 only recover their vitality when removed from this 

 obnoxious influence. This recuperative power is 

 not, however, shared equally by all varieties of 

 yeast, some possessing it in a far greater degree 

 than others. Dr. Lohmann also found that yeast 

 cells, after being exposed to sunshine, assumed a 

 shrunken and distorted appearance, showing that 

 insolation had produced a striking physiological 

 effect upon the structure of these cells. 



Professor Hansen published some years ago 

 a most interesting memoir on some of the char- 

 acteristic features of the moulds which are to 

 be found on manure heaps, in which he records 

 how light exerts a very important influence on 

 the manner in which the spore or fruit of these 

 lowly vegetables is set free or distributed. All 

 the various phases in the fructification process 

 ,of some of these moulds were carefully watched 

 by Dr. Hansen. He kept his caged specimens 

 near a window with an eastern aspect, and he 

 states that in the first instance the stalks in- 

 clined towards the light, but that afterwards they 



