176 Lectures on Bacteria. [$ xiv. 



of the creature, and not in the caterpillar only, but also in the 

 butterfly and even in the eggs, from which they may find their 

 way again into the young caterpillar. They are also found in 

 enormous quantities, filling the entire insect. Pasteur especially 

 has shown that these bodies belong to a parasite, which 

 penetrates into the insect, and multiplying at its expense pro- 

 duce the disease. If they are introduced with the food into the 

 intestinal canal of a healthy caterpillar, they are subsequently 

 found to have penetrated into the wall of the intestine, at first 

 one by one, afterwards in greater numbers, and to have spread 

 from thence into the other organs. 



The same or similar bodies have been found by different 

 observers in sundry other insects and articulated animals. 



It would appear from this brief description that the Cornalian 

 bodies resemble a small Bacterium, and specially a Micro- 

 coccus, and they have been regarded as such by many observers. 

 Nageli calls attention in his first communication to their relation- 

 ship to Micrococcus aceti. This view rested on the similarity 

 of form, and specially on the observation that they were frequently 

 united together in pairs, since this fact was regarded as an indi- 

 cation of their multiplication by successive bipartition. Their 

 bipartition was not directly observed at that time nor has it been 

 observed subsequently, and it is obvious that union in pairs may 

 be brought about in other ways. There was therefore experi- 

 mental proof that the bodies did multiply, but how they multi- 

 plied was not known. Then Cornalia, Leydig, Balbiani, and 

 also Pasteur put forward another view in opposition to the theory 

 that the bodies were Micrococci; they supposed them to be 

 totally distinct from Micrococcus and Bacterium, and to be 

 Psorospermiae, that is, states of peculiar low organisms, 

 Sporozoa or Sarcosporidia. Metschnikoff has recently and 

 distinctly confirmed this view; he states briefly that the 

 parasite of pe*brine consists of protoplasmic bodies having the 

 power of amoeboid movement, after the manner, that is, of the 

 colourless blood-cells described on page 135, and subsequently 



