6o4 



PATTERNS AND PROBLEMS OF DEVELOPMENT 



few examples that patterns of various plant spores present interesting 

 problems and also that development from spores often involves formation 

 of new axiate patterns originating as buds. These, like other buds, are 

 apparently primarily radial gradient systems resulting from local activa- 

 tions and become axiate by differential growth. Doubtless different gra- 

 dient systems of this sort, even in the same plant, may differ chemically 

 and physically and, consequently, may give rise to axiate patterns of 

 different kinds. The case of the Fucus egg (pp. 423-25) suggests that 

 many of these forms of reproduction and development still afford interest- 

 ing fields for experiment.^ 



<sz 



A B 



Fig. 187, A, B. — Schizogony of a schizogregarine, Schizocystis gregarinoides. A, multi- 

 nucleate stage; B, formation of merozoites by cell-budding and separation about each nucleus, 

 progressing from the posterior end anteriorly (after Leger, 1909). 



PATTERN IN RELATION TO CELL FORMATION IN SPOROZOA 



In many Sporozoa the formation of merozoites and sporozoites and, 

 in some forms, of gametes shows an interesting relation between pattern 

 and cell formation. The elongated uninucleate sporozoite of Schizocystis 

 gregarinoides, a schizogregarine, develops into a wormlike form (schizont) ; 

 this becomes multinucleate with nuclei coming to lie near the body sur- 

 face (Fig. 187, A); ^, cell body buds from the parent body about each 

 nucleus; separation into uninucleate cells results; and these elongate to 

 form merozoites (Leger, 1909). The separation into cells occurs progres- 

 sively from the posterior end anteriorly (Fig. 187, B), suggesting a slight 



^ References have been omitted from this section almost entirely except in connection with 

 figures reproduced from papers, because the morphological data appear in botanical textbooks 

 and because the purpose here is merely to call attention to a few examples of these patterns and 

 the questions arising from them. 



