Merging two files with merging line by line

Hi,

I have two files and i want to merge it like,

file1.txt
---------
abc
cde
efg

file2.txt
-------
111
222
333

Output file should be,
--------------
abc
111
cde
222
efg
333

Please suggest. Thanks.

Try:

paste -d '\n' file1.txt file2.txt

Thanks a lot. It is working fine.
Timely help.