1914] PICKETT—PROTHALLIUM OF CAMPTOSORUS 233 
of the apical region and even after the formation of the archegonial 
cushion or meristem. It is shown especially in the formation of 
various marginal outgrowths and in the plicate or crispate form of 
old prothallia. Such marginal structures, resulting from irregular 
Fics. 21-36.—Figs. 21-27, various marginal outgrowths; fig. 23, one-celled 
form Stowing directly from regular margin; see fig. 21@ for outgrowths bearing anther- 
a 8S. 28-36, various forms of apical cells and groups; fig. 36 is a of fig. 18 more 
ighly magnified; fig. 28, wholly lateral apical group, and fig. 31, apical group (@) 
de a sinus; all X 120 except small figures in figs. 28 and 29. 
cell multiplication having no connection with apical growth, are: 
also characteristic of Camptosorus. These marginal structures 
may be of one or of very few cells (figs. 6, 17, 56, 61), or may be 
of many cells and approach the dignity of lobes (figs. 7, 16, 58). 
The form of several such lobes is shown in figs. 21-27. 
The region of apical growth 
Although the prothallia may attain considerable size and even 
Mature gametes without the appearance of a typical V-form 
“pical cell or a distinct apical group, such a growing region is quite 
usual and typical. The appearance of the apical cell or group 1s 
