where do the number 0xcc9e2d51 come from in Murmur hash?

I just studied Murmur Hash in http://ift.tt/eMiZiP. And the Algorithm is as follows:

Murmur3_32(key, len, seed)

c1 = 0xcc9e2d51
c2 = 0x1b873593
r1 = 15
r2 = 13
m = 5
n = 0xe6546b64

hash =gets seed

for each fourByteChunk of key
    k =gets fourByteChunk

    k = k * c1
    k = (k << r1) OR (k >> (32-r1))
    k = k * c2

    hash = hash XOR k
    hash = (hash << r2) OR (hash >> (32-r2))
    hash = hash * m + n

with any remainingBytesInKey
    remainingBytes = SwapEndianOrderOf(remainingBytesInKey)
    remainingBytes = remainingBytes * c1
    remainingBytes = (remainingBytes << r1) OR (remainingBytes >> (32 - r1))
    remainingBytes = remainingBytes * c2

    hash = hash XOR remainingBytes

hash = hash XOR len

hash = hash XOR (hash >> 16)
hash = hash * 0x85ebca6b
hash = hash XOR (hash >> 13)
hash = hash * 0xc2b2ae35
hash = hash XOR (hash >> 16)

I can generally understand the source code, but I don't know where the number 0xcc9e2d51 come from. I googled the number 0xcc9e2d51, and I found many functions used this number. Is there anyone could tell me?