Langerhansâ cell histiocytosis. (redirected from Letterer-Siwe) A group of conditions characterised by proliferation of Langerhans cells, which are lymphoreticular cells. Langerhans cell aggregates are nodular, especially in the lungs, and are variably accompanied by eosinophils, foamy cells, neutrophils, and fibrosis. Prognosis.
The conditions needed for seeds to germinate vary from species to species. In general we can say that all seeds need water and warmth to germinate. Temperature. In general, most seeds will germinate at temperatures between 10C and 35C. Some seeds, however, need a period of cold before they will germinate.
The label on a grass seed package provides important information, including the germination rate. A rate of 90-95% is preferred, but some grass varieties will typically be found in the 80% range. The higher, the better. An 85% germination rate means that if you plant 100 seeds, 85 of them should sprout and grow. Realize that this rating system comes from the supplier doing a test in a laboratory.