134 MICROSCOPIC FUNGI. 



point of tlieir sui'face wliicli is nearest to one of tlie 

 stomata^ or pores of tlie leaf^ its slender tube^ and 

 to have tknist it througli those openings, with the 

 swollen extremity resting in the air-cavity situated 

 beneath the pore. If many days, or even weeks, 

 are allowed to pass, and the leaf is examined again, 

 or another leaf similarly treated, and kept in a 

 living and vigorous condition by remaining attached 

 to the parent plant, still no further change or 

 advance will be observed, the germs will appear 

 fresh, and still in the same condition. Hence it is 

 concluded that plants are not infected through the 

 medium of their leaves.. 



If the cotyledons, or seed-leaves, are watered 

 with similar impregnated water, a different result 

 has been observed to take place. The germination 

 of the tubes till their entrance at the stomata is the 

 same ; but, having entered, the swollen extremity 

 elongates, becomes branched, and takes all the 

 appearance of mycehum such as we at first 

 described. If the infected plant endures through 

 the winter, the mycelium endures with it, to recom- 

 mence vegetating in the spring. 



The experiments which Dr. de Bary performed 

 were all upon plants of the common garden-cress. 

 It will be unnecessary to repeat aU the details of 

 these, as given in the memoir recently pubhshed on 

 the subject, but it will suffice to give a summary of 

 results. In two series of plants cultivated at dif- 

 ferent periods from good seeds, one hundred and 



