182 REPRESENTATION OF THE 



has but a temporary existence, and is known as the suspen- 

 sor ; that subsequently generated is the true embryo, which 

 in the course of development protrudes an extension down- 

 wards (the radicle), and one directed upwards (the plu- 

 mule). 



The particulars now referred to appear to be the essen- 

 tial points in the process, and there is undoubtedly a close 

 correspondence in them, between the two kinds of plants. 

 The differences, which at first appear so great, seem to be 

 reducible to the following : 



1. The shedding of the fern-spores before any of the cel- 

 lullar growths are formed and, of course, before impreg- 

 nation while the phanerogamic ovule continues in situ till 

 the embryo is matured. 



2. The development from the spore, in its primary ger- 

 mination, of an external cellular growth or prothallium, 

 which afterwards simulates a cotyledon whereas generally 

 in the ovule no cellular body is formed distinct from the 

 common tissue of the nucleus. 



3. The formation of numerous archegonia in the sub- 

 stance of the prothallium, each with a germinal corpuscule 

 in its interior whereas in the ovule there is normally but 

 one such capsule viz., the embryo-sac. 



4. The frequent co-existence of spermatic capsules and 

 of archegonia in the Cryptogamia within the same prothal- 

 lium ; whereas in phanerogamic plants, the organs contain- 

 ing the corresponding elements i.e., the anthers and 

 germens are from the very first quite distinct structures. 



To estimate the importance of these diversities they will 

 require to be considered seriatim. 



That mentioned first the premature dispersion of the 

 seed-like bodies is certainly a very constant point, but it 

 cannot be held to be of a kind to destroy the general cor- 

 respondence of the course of -phenomena in the two cases, 

 for it is evidently a phenomenon of the same nature as the 



