77 o THE POPULAR SCIENCE MONTHLY. 



and thus exposing the young grub to attack as soon as it is born. Pas- 

 teur's own researches soon induced him to adopt the same view. 'Hie 

 tf pebrine microbe was long regarded as a true bacte- 



(jk & rium, successively described as Bacterium bombycis^ 

 * 0^0 ** Nbsema bombycis (Fig. 5), and Panistophyton ovale. 

 q ^ Balbiani's recent researches tend to show that it should 

 O o be assigned to another group, much nearer to animals, 



and designated Sporozoaria. These protista, still 

 &yci7 pebrine mi- regarded as plants by many naturalists, chiefly differ 

 o f rom bacteria by their mode of growth and reproduc- 



tion, in which they resemble the parasitic protozoaria, termed Psoro- 

 spermia, Coccidies, and Gregarinidw. 



In Sporozoaria, growth by fission, the rule in all bacteria, has not 

 been observed ; this distinction is fundamental. Sporozoaria multiply 

 by free spore-formation in a mass of sarcode substance (protoplasm), 

 resulting from the encysting of the primitive corpuscles (mother-cells). 

 The formation of numerous spores may be observed within the mother- 

 cells, having the appearance of pseudonavicellm or spores of gregari- 

 nidse and psorospermia (parasites of vertebrate animals). Balbiani 

 forms these organisms, which are found in many insects, into a small 

 group, which he terms Microsporidia. 



The ripe spores are the vibratile corpuscles of Cornalia. They 

 closely resemble the spores of some bacilli (B. amylobacter, for in- 

 stance), and their germination is likewise effected by perforation of 

 the spore at one end, and issue of the protoplasm from the interior. 

 This, however, does not issue in a rod-like form {Bacillus), but in that 

 of a small protoplasmic mass, with amoeboid movements, a character- 

 istic not observed in any bacterium (Balbiani). The other species of 

 silk-worms which have been recently introduced, notably the oak silk- 

 worm from China {Attacus Pernyi) f are attacked by microsporidia 

 analogous to those of pebrine. 



Pasteur has indicated the mode of averting the ravages of this dis- 

 ease. He has thus addressed the breeders : " If you wish to know 

 whether a lot of cocoons will yield good seed, separate a portion of 

 them and subject them to heat, which will accelerate the escape of 

 the moth by four or five days, and examine them under the microscope 

 to ascertain whether corpuscles of pebrine are present. If they are, 

 send all the cocoons to the silk-factory. If they are not diseased, allow 

 them to breed, and the seed will be good and will hatch out success- 

 fully. In a word, start with absolutely healthy seed, produced by 

 absolutely pure parents, and rear them under such conditions of clean- 

 liness and isolation as may insure immunity from infection." When 

 the disease is developed, fumigation with sulphurous acid is recom- 

 mended, or preferably with creosote or carbolic acid, which do not 

 affect the silk-worms (Bechamp), and which hinder the development 

 of microsporidia. These fumigations likewise keep the litter from 



