of the Vegetable Ovule. 



97 



two coatings, so very dissimilar in their nature, were produced 

 from a single ovular tunic, then the cord of the raphe ought 

 rather to be found in the nut, as that would correspond with 

 the inner layers of mesodermic tissue in which the raphe exists 

 in the primine ; whereas that cord of vessels is really imbedded 

 in the fleshy tunic, while the nut is free from vessels of any kind. 

 This is further shown in the general structure of the seed of 

 Magnolia, where the raphe passes in its usual course through 

 the tissues of the fleshy coating, from the base to the apex, when 

 it suddenly breaks through the endoderm, and arrives at a distinct 

 foramen in the chalazal extremity of the nut, which I have called 

 a diapyle, through which it passes, and soon becomes lost in the 

 thickened areole or chalaza of the inner integument. 



On the other hand, we may conclude either that the nut ori- 

 ginates in a development of the secundine, and that the tegmen 

 results from the tercine or membrane of the nucleus (which is a 

 very rational inference), or that the nut is of independent origin 

 (which is still within the range of probability). Indeed there is 

 nothing to prevent the possibility or probability of the formation 

 of an intraneous coat between the usual tunics in the growing 

 seed, subsequently to the closing of the micropyle of the ovule. 

 We frequently meet with a copious deposit of loose cellular tissue 

 between the testa and tegmen, or even between the latter and 

 the albumen ; and this deposition may become consolidated into 

 a distinct membrane, or hardened by solid deposits : wherever 

 there exists a budding-point, this may at any time take place. 

 We have proof of the actual formation of such a tunic between 

 the primine and secundine in the Gnetacea* ; and this, if applied 

 to the case of Magnolia, points to a far more probable cause for 

 the appearance of the hard tunic in the seed, than the impro- 

 bable suggestion of Schleiden and Gray, to which I have just 

 referred. 



Schleiden, although entertaining so many ideal fancies re- 

 specting developments, gives nevertheless a somewhat true ac- 

 count of the present state of our knowledge on this subject : he 

 says (/. c. p. 427) — "A greater confusion than that which pre- 

 vails in the theory of the seed-coats is scarcely conceivable ; the 

 most heterogeneous things are thrown together under one name ; 

 thoroughly identical ones are placed in different kinds of organs ; 

 and there is nothing for it, if we would not make greater con- 

 fusion, but to cut the thread and begin over again : the epidermis 

 of the seed is sometimes described as testa, sometimes as arillus ; 

 seed - membranes are introduced where no true integuments 

 exist." 



* According to the interesting details given by Griffith, Lindley's ' Ve- 

 getable Kingdom,' p. 233, where analytical figures demonstrate the fact. 



