No. 3.] Silkworms- in India. 145 



links of which are almost spherical in form. These two parasites are sometimes found 

 together and sometimes separated. 



" When the bacillus is abundant, death quickly follows its appearance, and the 

 disease, spreading rapidly, will sometimes destroy a whole school in a single day. 

 At times this bacillus appears so short a time before the spinning of the cocoon that 

 the worms are able to mount into the branches, and even make their cocoons and 

 become chrysalides. Then, however, the disease overcomes them, and their putrefaction 

 produces foul cocoons. This case is, however, more rare, and in general the bacillus 

 is not often found in the chrysalis. When the ferment alone appears the disease 

 progresses differently. The worms then show the same languor on the approach of 

 the spinning period, and the same indisposition to make their cocoons ; but even then 

 they mount the branches, perform their work of spinning, are transformed into chry- 

 salides, and these into moths, which may have a fine appearance. The silk crop may 

 even be exceptionally good ; but when this state has existed, when the worm has been 

 without its usual agility at the spinning time, when it has shown this apparent lazi- 

 ness, then, though the cocoons be of the firmest and the moths the finest, there will 

 exist a weakness, a constitutional debility, that will show itself in the next generation. 

 This is the only way in which flaccidity is hereditary, in this predisposition of the 

 worm to succumb to disease on account of the affection which weakened, but which 

 did not kill, the parent. 



" Flaccidity generally appears after some sudden change in the weather or temper- 

 ature, as, for instance, a thunder-shower, or a hot, heavy day. It is apt, too, to 

 follow the feeding of wet or fermented food. If the shelves go too long uncleaned 

 and begin to mildew ; if the worms are too crowded on the tables and their natural 

 respiration interfered with, flaccid subjects will soon appear in the school. These, by 

 their unhealthy excrement, soil the food of their neighbours, who quickly follow 

 them in the path of disease. It is thus that flaccidity becomes highly infectious. 



" No very satisfactory means have been proposed for combating this malady when 

 once it appears. It would be well, on the discovery of the first victims, to take the 

 worms remaining healthy into another apartment, and give them more space and 

 plenty of air. Attentive care may then save the crop, though by no means with 

 certainty. To avoid the disease one should breed only from eggs microscopically 

 selected, though even their circumstances may be against the silk-raiser and the crop 

 be lost through no apparent fault of his. 



" Grasserie. — This disease is of little importance, and has therefore received but little 

 attention. It is thus described by Maillot (Legons, Sfc, page 111) : — 'In the middle 

 of a school of worms in good condition it is not rare, as a molt approaches or just 

 before the spinning begins, to find here and there some worms which crawl slowly, and 

 have a shining, stretched, thin skin ; the body is of a bright yellow in the yellow, and of 

 a milky white in the white races ; a troubled liquid transudes through the skin, soiling 

 the food and the worms over which the diseased subjects pass .... A moist cold stagnant 

 air seems to favour the occurrence of grasserie. The disease is not contagious ; nor 

 does it appear that it can be transmitted, by heredity. From this point of view there is 

 nothing to be feared unless a great number die of the malady, in which case it will be 

 imprudent to use the stock for reproduction.' Victims of this disease should be 

 removed as soon as discovered, as they are apt to crawl into the branches and soil the 

 cocoons spun by other worms. 



"(Summing up the diseases to which silkworms are liable, we have: — 



" 1, Grasserie, which is never hereditary, as the victim never dies later than 

 in the chrysalis state, and the disease can never originate in the moth. 



B 



