Follow this example. I loop through all elements of M and then all columns within each element of M.
% fake data
M = {rand(74,3); rand(68,3); rand(22,4)};
% get number of columns in each M
nCols = cellfun(@(x)size(x,2), M);
% initialize loop vars
stats = cell(length(M), max(nCols));
bootsam = stats;
% Loop through your cell array
for i = 1:length(M) %for each element of M
for j = 1:size(M{i},2) %for each column of M{i}
[s,b]= bootstrp(100,@(x)[mean(x) std(x) moment(x,4) moment(x,3)],M{i}(:,j));
stats{i,j} = s; %store values
bootsam{i,j} = b; %store values
end
end
% To get the results for M{1} column(2)
stats{1,2}
bootsam{1,2}
