20 



MORPHOLOGICAL DEVELOPMENT. 



Where, as in types like these, tlie morpliological units 

 show an inherent tendency to arrange themselves in a man- 

 ner that is so far constant as to give characteristic propor- 

 tions, we may say that there is a recognizable compound in- 

 dividuality. Considering the Thallogens that grow in this 

 way, apart from their kinships, and wholly with reference to 

 their morphological composition, we might not inaptly de- 

 scribe them as pseudo-foliar. 



§ 184. Another mode in which aggregation is so carried 

 on as to produce a compound individuality of considerable 

 definiteness, is variously displayed among other families of 

 Ahjce. When the cells, instead of multiplying longitudin- 

 ally alone, and instead of all multiplying laterally as well as 

 longitudiQally, multiply laterally onty at particular places ; 

 they produce a branched structure. 



Indications of this mode of aggregation occur among the 

 Confertce and simple plants akin to them, as shown in Figs. 

 22, 23. Though, in some of the more developed AlgcB which 

 exhibit the ramified arrangement in a higher degree, the 

 component cells are, like those of the lower AlgcB^ united to- 

 gether end to end, in such way as but little to obscure their 

 separate forms^ as in Cladophora Hutchinsice, Fig. 31 ; they 



neTertheless evince greater subordination to the whole of 

 which they are parts, by arranging themselves more method- 



