208 CLASSIFICATION OF THE MICRO-ORGANISMS. 



The living animal shows diminished appetite, and becomes 



languid ; soon after death the bodies become soft and almost 



fluid ; after 24 48 hours they present a dark colour, and 



become filled with gases and blackish brown putrid fluid. 



The disease appears to develop "spontaneously" under 



unfavourable hygienic conditions^-bad ventilation and food, 



&c. ; it is also propagated by infection. The disease can be 



set up in healthy animals by feeding them with dust from 



affected localities. In the digestive tube of the diseased and 



dead animals, especially in the juice of the stomach, these 



O o o micrococci are constantly present in 



no00 o large numbers, and other bacteria also 



ooo 0o o^ appear shortly before death. Never- 



^ oo0 oc*s o theless there is no proof that all the 



\ morbid symptoms can be explained by 



% o o c * the distribution of the micrococci in the 



Fig. 50. Micrococcus bod ^' or that the minutest number of 



bombycis (afterCohn) the isolated organisms can induce the 



x 60 - disease ; there is, therefore, a possibility 



that other bacteria more difficult to demonstrate are the true 



exciting agents of the disease. 



Febrine Nosema bombycis (Micrococcus ovatus, Panhistophyton ovatum, 



corpuscules du ver a sole), the cause of the pebrine (Oattine, 



Fleckenkrankheit, maladie des corpuscules) of the silkworms 



a may be included here, although 



0""'c\ o from the size and form of the 



* *& %&- b or g anisms J as wel1 as from the 



^ ? Q> imperfect knowledge of their 



a Q ^ 8 b developmental history, we are 



Q still doubtful as to their proper 



Fig. 51. Nosema bombycis P lace - In the blood and in a11 



X 500. the organs of the diseased worms 



a, Nosema cells. we find highly refracting oval cells, 



' b, urates which are usually 3^ long< 2 ^ broad; for the 



present in the prepara- . ^ . ' . 



tions. (After Duclaux.) most part isolated, at times united 



in pairs or masses. They were 



first discovered by Cornalia, and subsequently described by 

 Lebert, Nageli, and Pasteur. Recently Metschiiikoft' has 

 supported the supposition formerly entertained, that the 

 exciting agents of pebrine belong to the psorospermese. 



The disease is characterised by the appearance of blackish 

 patches on the skin of the caterpillars. At the same time the 

 appetite diminishes and the worms become more slender and 

 watery ; the silk organ swells up in a garland form, becomes 

 opaque, and the diseased worms furnish no coccooiis, or only 

 very weak ones ; finally, they die after a short time. The 

 whole organs then appear to be infiltrated with the " micro- 



