PHYSIOLOGY OF THE RED MANGROVE. 625 



A great deal of work has been done by Guppy^^ on plant dis- 

 persal and in one work he has devoted several chapters to the 

 mangrove and on page 451 of the above book gives the "history of 

 the reproductive process in Rhizophora from the fertilization of the 

 ovule to the falling of the plantlet or seedling from the tree." He 

 goes on to say: "I devoted great attention to this subject in the 

 instance of Rhizophora mangle, being desirous of determining two 

 points, in the first place as to whether there was any period of rest 

 between the maturation and germination of the seed, and in the 

 second place as to the period that elapsed between the commence- 

 ment of germination and the fall of the seedling." " The principal 

 change in the ovary for the first three or four weeks after fertili- 

 zation is shown in its increased breadth. The increase in height is 

 but slight during this period ; and in fact after thirty days the ovary 

 only added two millimeters to its original height of three millimeters. 

 After this the growth of the fruit proceeds until the tip of the 

 radicle pierces its summit, the fruit being then about eleven lines 

 (2.8 cm.) long. From the date of fertilization to the time the radicle 

 pierces the top of the fruit a period of about fifteen zveeks elapses. 

 (The fruit, it should be here remarked, continues to grow in length 

 and breadth after the radicle has protruded, attaining a length of 

 thirteen or fourteen lines (3.5 cm.) when the seedling or 'keim- 

 ling' is ready to fall.) " 



" It will be observed that there is no period of rest in the growth 

 of the fruit up to the date of the protrusion of the radicle. It may 

 also be shown that there is normally no pause between the epoch of 

 the maturation of the seed and the beginning of germination or, 

 in other words, that from the time of the fertilization of the ovule 

 to the onset of germination there is no cessation in the process of 

 growth of the embryo. That period of dormant vitality which al- 

 most all seeds pass through forms no normal feature in the life- 

 history of this species of Rhizophora." 



In Guppy's more recent work^^ of 1917 in the West Indies and 

 the Azores he gives a summary likewise of the period which elapses 



9c Gupp3-, H. B., " Observations of a Naturalist in the Pacific," Vol. H., 

 1906. 



9^ Guppy, H. B., " Plants, Seeds and Currents in the West Indies and 

 Azores," London, 1917. 



