I, and a friend who has a wonderful collection of natives, have discussed this problem with California frits sort of melting. It is a very common problem, and often occurs after repotting apparently healthy bulbs. Large mature bulbs can also disappear, leaving tiny rice grains or offsets. Personally, I think it is because the bulb is vulnerable to fungal diseases, and the lack of a tunic makes it very susceptible to damage that may not be apparent to the naked eye. I had a couple of e-mails regarding similar behavior with Lachenalias, the bulbs of which are similar to Fritillarias. I think it is advisable to treat such bulbs with a fungicide when repotting, but, even doing this, some disappear. California fritillarias are very touchy bulbs, difficult to grow even in their native environment. Diana Telos Rare Bulbs