Complex sentence: The images were inserted in places in the text left open for them, and in some cases the blank space has not been filled, strongly suggesting that when the manuscripts were sent to Spain they were as yet unfinished.
Split into simpler sentences: The images were inserted in places in the text left open for them, and in some cases the blank space has not been filled. This strongly suggests that when the manuscripts were sent to Spain, they were as yet unfinished.