Nov. 1899.] BOTANICAL SOCIETY OF EDINBUEGH. 235 



life-history, but which, in one stage of its history, looks 

 like a bacterium. 



There is, as Dr. Man son goes on to say, one well 

 authenticated instance of such a bacterium, the Micrococcus 

 Mflitcnsis, the cause of ]\Iediterranean fever. There are, 

 however, other diseases, 'sometimes classed as bacterial, 

 which are caused not by Schizomycetes, such as bacteria 

 and bacilli are, but by plants like the Streptothrix of 

 Actinomycosis, a disease common among cattle, and 

 occasionally found among human beings, and the Strepto- 

 thrix of Madura foot disease, an exceedingly common 

 disease among human beings in Southern India, and in 

 various other parts of the tropics. 



These plants are not unicellular masses of protoplasm, 

 but are composed of branched filaments, enclosed in a 

 sheath, and reproducing by Conidia, like some of the 

 higher fungi, not by simple division, or by solitary resting 

 spores. , 



They have a complex life-history, having an independent 

 existence outside the body of the man or animal which 

 they attack. 



In the case of Actinomycosis, there can be little doubt 

 that, outside the bodies of cattle, the microbe exists as a 

 parasite on various species of grain, generally barley, 

 and that the animal is infected by eating this barley. 



It is very important to keep clearly before our minds 

 the distinction between a protophyte and a metaphyte, for 

 the following reason : — 



Protophytes multiply by simple division, so that it is 

 easy to understand why, in their case, acquired characters 

 are transmitted. Each of the new plants is simply one- 

 half of the old one, neither more nor less. 



In metaphytes, special cells are set apart early in the 

 life-history of the plant for reproduction, and experience 

 shows that characters acqviired by the somatic cells do 

 not pass to the reproductive cells, and are therefore not 

 transmitted to the progeny. Why this should be so 

 nobody knows. But the business of science is to ask 

 the " hoio " of everything, the " whij " of nothing. 



Science has nothing to do with the word " ivhy." It 

 is probable, though not proved, that acquired characters 



