from The Century Dictionary and Cyclopedia
- Germinating from the surface of the ovum: noting those meroblastic eggs which, by superficial segmentation of the vitellus, produce a perigastrula in germinating.
Sorry, no etymologies found.
In the periblastic the food-yelk is in the centre, enclosed inside the ovum (hence they are also called "centrolecithal" ova): the formative yelk surrounds the food-yelk, and so suffers itself a superficial cleavage.
According as the yelk-food accumulates at the centre or at the side of the ovum, we distinguish two groups of dividing ova, periblastic and discoblastic.