108 Transactions, &c. — Annual Address. 



of beads. These bodies have their origin in a fermentation of 

 the mulbeny-leaves. The investigations of M. Pasteur estabUsh the 

 feet that bodies belonging to the class of ferments can be causes of 

 disease, and they afford a striking instance of the value of the micro- 

 scope in detecting such causes, and checking their action. The chief 

 silkworm diseases arise from objects which the microscopist furnished 

 with the data supphed by Cornaha, Quatrefages, and Pasteur can 

 recognize with certainty, but the same cannot be said of other bodies 

 known or supposed to have morbific properties, some of which are 

 ahke in appearance, while others, more susceptible of discrimination, 

 bewilder an investigator when he tries to trace certain consequences 

 back to them as an efficient cause. 



Dr. Burden Sanderson considers it probable that " every kind 

 of contagion consists of particles ; " but then come the questions of 

 'WTiat are these particles ? What is their origin ? and How can we 

 discriminate one from another. Pieferring to HaUier's researches 

 and discovery of colonies of micrococci in every contagious liquid, 

 he observes: "Assuming this observation to be correct, and that, 

 as HaUier believes, the microzymes are identical with the con- 

 tagious particles, it is of no value as a means of distinguishing the 

 various contagia from each other, unless the micrococci are capable 

 of differentiation ;" which last words seemed to be used inadvertently 

 for susceptible of discrimination. " HaUier," he continues, " admits 

 at once that no specific distinctions can be founded on their forms or 

 appearances, as actually observed in contagious hquids. He seeks 

 for the required characteristics in their development, and maintains 

 that, although the microzymes of two different classes are exactly 

 the same, the higher forms to which they severally unfold are spe- 

 cifically distinct." He goes farther than this: from the higher 

 forms obtained by cultivation he claims to be able to reproduce con- 

 tagious microzymes. Dr. Sanderson does not consider that Hallier 

 has proved his case, and this seems to be the general opinion in this 

 country ; but what is here said may induce Fellows of this Society 

 to make experiments with the lower foiTQs of life, and work out dis- 

 puted or doubtful points of fungoid development. Among the 

 fungi to which Halher imputes disease is the Pleosjpora herharum, 

 the form that is parasitical on darnel being in his opinion the cause 

 of sheep-pox — a thing which Dr. Sanderson observes has not been 

 tested by actual experiment. 



^Vhether we call the organic particles in question " bioplasts," 

 or " microzymes," whether we suppose them animal or vegetable, 

 and whatever theory we form as to theii* origin, there are three 

 conspicuous modes by which they may become disseminated, viz. 

 by water, or by air, or in food either liquid or solid. The Yearly 

 Report on Public Health, by Mr, Simon, published last year, con- 

 tains a paper by Dr. Thorne, " On the Effects produced on the 



