222 REPORT OF THE COMMISSIONER OP AGRICULTURE. 



their base seeking some place to spin their cocoous which it requires no 

 exertion to attaivi. ]Many of tho.^e wliicii reach the branches stretcli 

 themselves out motionless on the twigs and die there Thej" aie to be 

 se(M) later hanging by their prolegs in different states oC putrcCiictirn 

 (LMatc 11, Fig. 1). When these symptoms are observed we may be sun*, 

 that the worms are attacked by llaccidity {Jiacherie). 



Nature and Treatment. — A full discussion of the causes of and treat- 

 ment for this disease will be given in Bulletin No. 9, of this Division. 

 ( hir present object is only to describe the indications of the malady with 

 sucli fullness that it may be readily known to the silk-raiser. Sviu-re 

 the symptoms given above are not sufficiently obvious, and where it is 

 necessary to make assurance doubly sure, a microscopic examination of 

 the intestines of the sick worm should be resorted to. Ilere will be 

 found masses of undigested food, and the coats of the intestines will be 

 found to be opaque. Here, too, the microscope reveals the parasites 

 ordinarily attending putrefaction, chief among which is a bacillus, seen 

 sometimes with and sometimes without a bright nucleus. There also 

 exists a special form of ferment, not unlike that which accompanies the 

 formation of vinegar {Mycodenna aceii Pasteur), which is found in short 

 chains, the links of which are almost spherical in form (Plate III, Fig. 1). 

 These two i)arasites are sometimes found together and sometimes sepa- 

 rately. When the bacillus is abundant death quickly follows its ap- 

 pearance, 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 chrysa- 

 lides. Then, however, the disease overcomes them and their putrefaction 

 produces foul cocoous. 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 j but even then they mount the 

 branches, perform their work of spinning, are transformed into chrysa- 

 lides, and these into moths which may have a fine appearance. The 

 silk crop may even be exceptiouably good ; but where this state has 

 existed, when the worm has been without its usual agility at the spin- 

 ning time, where it has shown this apparent laziness, then, though the 

 cocoons be of the firmest and the moths the finest, still there will exist a 

 weakness, a constitutional debility that will show itself in the next gen- 

 eration. This is the only way in which fiaccidity is hereditary, in this 

 predisposition of the worm to succumb to disease on account of the af- 

 fection which weakened but which did not kill the parent. 



When these apparent troubles are seen, we need look no farllicr fcr 

 signs of the malady, but at once reject the stock as unfit for reproduclion. 

 But, as it is not always possible for the egg-producer to have tiuis 

 watched the rearing of the worms, it will be well to describe a. meat's 

 by which fiaccidity maybe detected in the chrysalis, so that if the stock 

 be unfit for tig<y production the cocoons may be stified and their vahic 

 not injured by the emergence of the moth. For this purpose we can do 

 no better than give a translation of the instructions published by M. 

 Pasteur ou this point, with their accompanying illustrations.* They are 

 as follows : 



" Cut away the wall of the thorax of the chrysalis with fine scissors, 

 as shown in Plate II, Fig. 2, so as to reveal the stomach s. Draw this 



* £tude3 Sur la Maladie des Vers a Sole, vol. i, p. 233. 



