6 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17 



then, in a way assumes that a seed is ripe or mature, and if it is 

 ripe or mature the embryo has become dormant, sometimes even in 

 an immature state. Presumably the embryo of a "ripe" seed is en- 

 tirely mature or at rest. On the other hand it may be that immature 

 seeds "germinate" because they are able to continue growing without 

 becoming mature or entering into a state of rest. 



The development of the seed from the fertilized egg cell in the 

 ovule is a process of growth which involves not only the embryo 

 itself which has to attain a certain size before it becomes dormant, 

 but also the storage of reserve food either in the cotyledons, which 

 are a part of the embryo, or in the form of endosperm which goes 

 to make up the bulk of the "seed" or that part which is enclosed 

 within the seed coat. When the reserve food is deposited in the 

 cotyledon, or in the form of endosperm, the deposition continues 

 to go on until the seed has reached a practical state of maturity. 

 The external evidences of this stage are the usual ones which we 

 are accustomed to associate with ripening seeds and which, of course, 

 vary with the different species. In peas, for example, maturity is 

 indicated by the hardening or drying of the pod and this, upon being 

 opened, discloses that the seeds themselves are hardening and chang- 

 ing to a darker color. 



In this experiment no provisions were made for morphological 

 studies of the seeds so that the exact condition of the embryos at 

 particular stages was not determined. Seeds were collected in two 

 stages of immaturity. As nearly as could be determined, these were 

 when "half ripe" and "nearly ripe." For various reasons it was possible 

 to secure immature seeds, particularly in the half ripe stage, from 

 but four species, and of the nearly ripe stage from only nine species. 

 Fully ripe seeds were collected from twenty-two species. In all cases 

 the seeds were planted in moist sand in the greenhouse. 



TABLE 1. GERMINATION TEST WITH HALF RIPE SEEDS 



This preliminary test, while very incomplete in that it covers but 

 little ground, is of interest because it shows that seeds of many an- 

 nual plants are able to germinate when still quite immature, and the 

 percentage that grow average as high as the growth from mature 



