FUNCTION.] OF TROP^OLUM. 231 



umbilical cord or funiculus, which terms it would be well to 

 confine to the suspensor alone; while the former might 

 retain the appellation of podosperm as referring to its relation 

 to the ovule. 



ee As it is necessary that an umbilical cord should be 

 organically united with the embryo, the impropriety of 

 considering the organ described by Malpighi in that light 

 will become sufficiently obvious. This structure consists of 

 a minute cellular process extending from the base of the 

 embryo-sac to the base of the nucleus, and has been found 

 chiefly in the Cucurbitacese and Rosacese. It appears) how- 

 ever, to be but a mere appendage of the embryo-sac, from 

 which it takes its origin, and often never reaches the base of 

 the nucleus, and therefore cannot be the medium of nutrition 

 even to the embryo -sac. To this organ, therefore, it would 

 be better to confine the term applied to it by Dutrochet, and 

 name it the hypostate, as pointing out merely its anatomical 

 relations. The cellular process proceeding from the extremity 

 of the suspensor, next the exostome, around the outer surface 

 of the ovule into the carpellary cavity is an organ of somewhat 

 unusual occurrence, but from its mode of growth and struc- 

 tural relations, it may be inferred to be of very essential 

 importance to the origin and development of the embryo. 

 Now it has been recently pointed out by F. G. F. Meyen, 

 that in the great majority of instances the pollen-tube, after 

 having penetrated the micropyle, is brought in contact with 

 the apex of the embryo- sac, with which it there contracts an 

 adhesion ; from this period the changes consequent on impreg- 

 nation date their commencement ; and, under the direct 

 influence of this immediate application of the fovilla to the 

 embryo-sac, continue with uninterrupted regularity. But in 

 the case of Tropseolum majus, as the pollen-tube never 

 reaches the embryo-sac, some additional means are required 

 to insure that influence of the fovilla on the primary utricle 

 which is necessary for the development, at its extremity of the 

 spherical cellular body, which subsequently becomes the 

 embryo. This action, then, is effected by the projection of 

 this cellular process from the primary utricle, which, by being 

 immersed (so to speak) in the fovilla, is made the medium 



