1889.] MICKOSCOPICAL JOURNAL. 7 



herd the well animals are not affected for a day or more, if at all. If 

 the sick animal gave off' an injurious gas, the chemist will tell you that 

 it would begin to show itself at once. There are no chemical sub- 

 stances which take such a long time to operate. It seems, therefore, 

 that it must be a very small amount of an invisible substance. But if 

 the substance is too small in amount to cause the disease at once, why 

 does it cause it after several days ? The answer is that the substance, 

 whatever it is, must have increased ; it must have the power of growing 

 at the expense of the animal. If it does so increase and multiply, it 

 must be a living being of some sort — either an animal or a plant. And 

 it is now known to be plants of a different sort in each disease. 



These, of course, are purely theoretical reasons, but they are so logi- 

 cal that they have rapidly won conviction. About the same time that 

 Henle, in Germany, arrived at these conclusions, an American, Dr. J. 

 K. Mitchell, also came to the same opinion, independently. From this 

 time to 1876 a great deal of work was done to prove the connection 

 between bacteria and disease. It had already been proven in 1837 by 

 Cagniard, Latour, and Schwann, independently, that fermentation is 

 due to yeast fungi, and Pasteur and others had also done valuable work, 

 but it was reserved for Robert Koch to establish in the manner already 

 described that for malignant pustule and other diseases bacteria are the 

 cause. 



Since 1S76 bacteriology has developed into a science of itself, in 

 which are engaged numbers of specialists. The laboratories in Europe 

 and in America give evidence of the interest and zeal with which the 

 subject is being studied. Not only have the physicians and veterina- 

 rians found it of great benefit in their branches, but agriculturists and 

 chemists as well. 



Report upon the Postal Club Boxes— II. 



By QUEEN MAB. 



Box cd. — The charm and value of the Cole Studies consists in their 

 being real studies, and not superficialities. The text accompanying the 

 slides gives the etymology, their megascopic and microscopic character- 

 istics, together with illustrations of the objects, their mode of prepara- 

 tion, and the bibliography of the subject. 



Slide No. 1 contains a transverse vertical section of the blade of a 

 foliage leaf of Rhododendron ftonticum, selected because of the excel- 

 lent tvpe it affords of leaf structure. The leaf was decolorized in al- 

 cohol previous to cutting, was stained with logwood, and amounted in 

 Canada balsam. 



Slide No. 2 is a vertical section of cluster cup, ^Ecidittm composi- 

 tarum var. tussilaginis, in situ on leaf of Ttissilago farfara. It 

 shows two yEcidia on the lower surface of the leaf, and one spermogo- 

 nium, which, as usual, is on the upper surface and directly above the 

 sEcidium cup. The method of preparation should be as follows: — 

 The freshly gathered leaf with its parasitic growth should be sliced be- 

 fore it has time to decay, or be preserved in a 50°^ solution of alcohol. 

 The sections maybe mounted in glycerine, glycerine jelly, or Farrant's 

 liquid. If allowed to drv, the spores maybe wet in turpentine and 



