40 
Proceedings of Royal Society of Edinburgh . [sess. 
mann,* on the influence of light on the Purpurin bacteria. We 
may, accordingly, regard the protoplasm as having several adapta- 
tions, latent memories ready to spring into action on the application 
of the appropriate stimulus. 
As we have already seen, the enzyme faculty is to be regarded as 
a differentiation of a primitive power of the protoplasm, and we 
have now to consider the probable cause of its origin. The resolu- 
tion of the complex into the simpler, more diffusible molecules, is 
accompanied by the setting free of a certain amount of energy which 
is lost to the organism when this occurs by means of enzymes 
in the external medium. What compensating advantage could its 
development entail on the organism ? From experiments on anaero- 
biosis, I was led to suggest some time ago, that; under this condition, 
where the enzyme action appears cut off, the organism was more 
sensitive to acid reaction. Further investigation has indicated so 
clearly a relation between the loss of this function and a corre- 
sponding increase in sensitiveness of the organism to injurious 
agencies, that this view becomes more than a mere hypothesis. The 
development of enzymes, by which the complex indiffusible com- 
pounds which supply it with nourishment are rendered diffusible 
outside the organism, would allow of the protoplasm being invested 
by a firmer, resisting, bounding membrane; and as this function 
was gradually evolved, each stage of development would be asso- 
ciated with a corresponding condition of the cell membrane. In a 
similar way each loss of this function would be accompanied by a 
change in the membrane, rendering it more sensitive to external 
injurious agencies. We must now consider how far this accords 
with a series of facts which have lately been observed by Fliigge. 
Fliigge f has come to the conclusion that Pasteur’s anthrax and 
fowl-cholera vaccines are really degenerated cultures, in which the 
protoplasm as a whole has suffered by the devitalising conditions 
to which they have been exposed during their production. He 
founds this view on a series of very careful experiments, which indi- 
cated that the attenuated cultures grew less rapidly than the 
virulent, and were also much more sensitive towards antiseptic 
agents. In addition, they grew more slowly and were more sensitive 
* Archiv f. d. ges. Physiologie, Bd. xlii., 1888. 
t Zeitschrift fur Hygiene , Bd. iv., 1888. 
