PARTS CONCERNED IN REPRODUCTION. 237 



Vegetable Spermatic. 

 Fovilla within the Pollen- 

 tube. 



Pollen grain. 

 Primary Pollen-cells. 



Parenchyma of Anther. 



Vegetable Germinal. 

 Protoplasmic Corpuscules. 



Embryo-sac. 

 Nucleiis of Ovule. 

 Ovule. 



3. By way of applying the principles of homological 

 correspondence to the specialities of the several groups of 

 organized heings, a few tabular statements are here sub- 

 joined, based on the notices of the reproductive process in 

 Chapters II. and III. : 



PROTOMORPHIC STAGE. 



The primary product of fecundation, (pro-scolex passing 

 into scolex,) is represented 



In Diatomacese, by the large frustules. 



In Algae, Fungi, and Lichens, by the composite 



spores. 



In Mosses and Hepaticse, by the seta and theca de- 

 veloped from the archegonial cell. 

 In the higher plants, only by the cellular suspensor 



of the embryo of the seed. 



It is" represented in Animals by the primary germmass, 

 which in many Invertebrata has the characterof a ciliated 

 animalcule. In general it attains no higher organization ; 

 but 



In Echinodennata it is developed into such zooids 



as Auricularia, Pluteus, and Bipinnaria. 

 In Trematoda, into the primary gregariniform zooid 



(redia or sporocyst). 



In Cestoidea, into the Cysticercus or the primary 

 vesicle of the Echinococcus. 



