320 WiscONsiif State Horticultural Society. 



were tubes. The same experiment was repeated in the open air, 

 outside the cow-house, with the same result; every tube contained 

 germs, most of them of different kinds, some of orange color, 

 some pink, green, and different shades, varieties he had not seen 

 before. Still another experiment was made with twelve more tubes. 

 The cow was driven to the orchard in the morning, just after a 

 shower had cleared the air, and the conditions were the most 

 favorable possible ; yet in ten of the twelve tubes the germs were 

 developed within a day or two. 



The germs found in the atmosphere are mainly spores, or the 

 seeds of the perfect plant or organism, and they have a general 

 resemblance both in form and size to each other ; so much so, that 

 if judged by this we should conclude that there were but very 

 few varieties. But when placed in proper conditions for growth 

 a great variety of form is seen. When full grown, some are round 

 like a ball, others oval ; some resemble rods of varied lengths 

 and outline, rectangular, tapering and obtuse ; others are long, 

 fiber-like, straight or curved, wavy and spiral. In some, these 

 peculiarities are quite marked and easily seen, in others very in- 

 distinct; so much so as to make it very difficult to determine to 

 which variety they belong. When we take into consideration 

 their minuteness in size, we shall more readily appreciate the diffi- 

 culty of deciding what they are, so as to say definitely whether 

 they belong to this or that class. The differences between a horse 

 and a mule are discernible at a glance when they are of their 

 natural size, but reduce them so that a magnifying power of two 

 thousand diameters is required to make them visible and the 

 differences would not be at all appreciable, though still there ; so 

 it is with these minute bodies. Professor Ferdinand Cohn says 

 on this point, " so long as the makers of our microscopes do not 

 place at our disposal much higher powers and as far a possible 

 without immersion, we will find ourselves in the domain of 

 bacteria, in the situation of a traveler who wanders in an un- 

 known country, at the hour of twilight, at the moment when the 

 light of day no longer suffices to enable him to clearly distinguish 

 objects, and when he is conscious that notwithstanding all his 

 precautions he is liable to lose his way." 



