b30 
Allgemeines. 
It is suggested that the behaviour just mentioned of Eurotium 
“indicates that we are dealing with a definite series of changes 
which are inhibited by the presence of too much available nutriment 
supplied at a temperature too low to enable it to be sufficiently 
rapidly altered within the organism so as to give rise to the 
specific substance which is more directly responsible for the 
ascogonial phase of the life-history.” The ‘fairy rings’ of agarics are 
probably of an analogous character, and such rings may easily be 
produced on artificial cultures of moulds by various means. If the 
nutrient agar be kept fairly dry so that the rate of diffusion of 
soluble material is slowed down it is found that concentric zones of 
sporiferous and sterile hyphae regularly alternate with each other. 
An explanation of this behaviour which seems most probable is 
that the hyphae after growing over the substratum for a certain 
distance acquire sufficient raw material to provide for the building-up 
of the substance which stimulates spore-production. When the 
substance is used up spore-production ceases until a fresh supply of 
material has been gained. This Suggestion is supported by the fact 
that interference with the circular form of the zones can 
be brought about by artificially intertering with the rate 
of diffusion of the nutrient substances in the jelly. The 
rhythmical alternation of sterile and fertile zones seems to prove 
that quantity of elaborated material is an essential factor in the 
process. The striking parallelism is pointed out between the nutritive 
i. e. Chemical Stimulus in the case of the fungus and the minimal 
time Stimulus required to provoke geotropic movement; for in the 
latter case there is evidence of a definite Chemical change as a 
result of the disturbance of normal gravitational relations, for 
Czapek has shown that there is an accumulation of homogentise- 
nic acid. 
The physical conditions of cellular constituents are clearly ol 
great importance in modifying the course of Chemical changes. 
Water must play a particularly important part in reactions which 
are occurring in a mixture of colloids such as the various proteins 
in the cell; questions of rates of diffusion, physical adsorption and 
the remarkable electrica] relations exhibited by the proteids have 
all to be taken into account. 
The importance of the study of the Chemistry and physics of 
karyokinesis is pointed out; and in connection with this the objection 
to the histological method of studying coagulation or precipitation 
figures is considered. It is made clear that provided these precipi- 
tations or coagulations faithfully map out the positions of the 
respective colloids during life there is no face in the objection. The 
study of the living cell during division indicates that the requisite 
degree of faithfullness is attained. The explanation of some of the 
remarkable changes undergone by the linin and chromosomes during 
mitosis as due to disturbances of an electric nature is discussed, 
especially the increase in size of the nucleus and the apparent 
mutual repulsion between the chromosomes which occur in the 
diakinesis stage of the heterotype division. For details reference 
must be made to the original paper. 
The great similarity of the changes occurring during division 
of the nuclei of animals and plants point to the-fact that these 
phenomena have little direct relation with the more specialized forms 
of metabolism on which the properties of specific form etc. depend. 
The Suggestion is made “that the processes actually involved 
