456 TRANSACTIONS OF SECTION D. 



correct to call it so, becomes correspondingly increased in quantity. I will not 

 attempt, however, to follow up the evolution of the bacterial type further, nor 

 to discuss what other types of living organisms may be affiliated with it, as I 

 have no claims to an expert knowledge of these organisms. I prefer to leave 

 to competent bacteriologists and botanists the problem of the relationships and 

 phylogeny of the Cyanophycese, Spirochsetes, &c., which have been regarded as 

 having affinities with Bacteria. 



(2) In the evolution from the biococcus of the predatory type of organism, 

 the data at our disposal appear to me to indicate very clearly the nature of 

 the changes that took place, as well as the final result of these changes, but 

 leave us in the dark with regard to some of the actual details of the process. 

 The chief event was the formation, round the biococci of an enveloping matrix 

 of protoplasm for which the term periplasm (Lankester) is most suitable. _ The 

 periplasm was an extension of the living substance which was distinct in its 

 constitution and properties from the original chromatinic substance of the 

 biococcus. The newly-formed matrix was probably from the first a semi-fluid 

 substance of alveolar structure and possessed two important capabilities as the 

 result of its physical structure; it could perform streaming movements of 

 various kinds, more especially amoeboid movement; and it was able to form 

 vacuoles internally. The final result of these changes was a new type of 

 organism which, compared with the original biococci, was of considerable size, 

 and consisted of a droplet of alveolar, amoeboid periplasm in which were 

 imbedded a number of biococci. Whether this periplasm made its first appear- 

 ance around single individual biococci, or whether it was from the first asso- 

 ciated with the formation of zoogloea-like colonies of biococci, must be left an 

 open question. 



Thus arose in the beginning the brand of Cain, the prototype of the animal, 

 that is to say, a class of organism, which was no longer able to build up its 

 substance from inorganic materials in the former peaceful manner, but which 

 nourished itself by capturing, devouring, and digesting other living organisms. 

 The streaming movements of the periplasm enabled it to flow round and engulph 

 other creatures ; the vacuole-formation in the periplasm enabled it to digest ami 

 absorb the substance of its prey by the help of ferments secreted by the biococci. 

 By means of these ferments the ingested organisms were killed and utilised as 

 food, their substance being first broken down into simpler chemical constituents 

 and then built up again into the protein-substances composing the body of the 

 captor. 



A stage of evolution is now reached which I propose to call the pseudo- 

 moneral or cytodal stage, since the place of these organisms in the general 

 evolution of life corresponds very nearly to Haeckel's conception of the Monera 

 as a stage in the evolution of organisms, though not at all to his notions with 

 regard to their composition and structure. The bodies of these organisms did 

 not consist of a homogeneous albuminous 'plasson,' but of a periplasm corre- 

 sponding to the cytoplasm of the cell, containing a number of biococci or chro- 

 matin-grains. Thus their composition corresponded more clearly to that of 

 plasson as conceived by Van Beneden, when he wrote : 'Si un noyau vient a 

 disparaitre dans une cellule, si la cellule redevient un cytode, les elements 

 chimiques du noyau et du nucleole s'etant repandus dans le protoplasme, le 

 plasson se trouve de nouveau constitue.' If we delete from this sentence the 

 word 'chimiques' and also the words ' et du nucleole,' and substitute for the 

 notion of the chemical solution of the chromatin-substanice that of scattered 

 chromatin-grains in the periplasm, we have the picture of the cytodal stage of 

 evolution such as I have imagined it. It should be borne in mind that the 

 ultimate granules of chromatin are probably in many cases ultra-microscopic : 

 consequently they might appear to be dissolved in this cytoplasm when really 

 existing as discrete particles. 



In the life-cycles of Protozoa, especially of Rhizopods, it is not at all infre- 

 quent to find developmental phases which reproduce exactly the picture of the 



grains in Bacteria. Vejdovsky compares them with chromosomes; but there is 

 no evidence that they play the part in the division and distribution of the 

 chromatin-grains which is the special function of chromosome."?, as will be dis- 

 cussed in more detail presently. 



