Auff. 1919.] TUE f 'OR RELATION IN 'Uf/C DIFFERENTIATION. |65 



ferrcd to 0.5 per cent solution in order to determine if any antheridia 

 were formed on tlicse pieces. When examined on twent^'-foitr days later, 

 the adventitious growth had already begun from the margin of the cut 

 ends of the pieces and of the original prolhallia. Many rhizoids were 

 also found at the detached ends of the former. Later the adventitious- 

 ly grown portions formed the growing jioints and finally antheridia 

 were produced on them Init not on the original prothallia. No arche- 

 gonia were found till at the end of the experiment. It may be born in 

 mind that the untreated prothallia formed no antheridia at th«i#ame 

 period of the experiment. We sec therefore that the archegonia-bearing 

 prothallia of Woodwardia are not incapable of forming antheridia by the 

 concentration of the nutrient solution which is high enough to induce 

 the formation of nrehegonia when they were grown normally. The 

 condition of archegonia formation must exert some kind of influence 

 on the formation of antheridia throughout the entire organism,- even 

 the archegonia are formed at the limited portion of the prothallium 

 When a part is detached from the whole, the established relatiem is 

 no longer maintained and the formation of antheridia becomes possible 

 at newly grown part of the detached piece. 



The relation between the archegonia formation and the grow^th of 

 the prothallia is already mentioned. When the growing point is 

 broken up, the irregular growth begins and the formation of arche- 

 gonia is suppressed. Antheridia may liowevcr be produced or the 

 prothallia may remain purely "i vegetative state. This is to indicate 

 that the capacity of producing archegonia is dijninished or inhibited by 

 the rejuvenescence of the " vegetative " cells. 



In the sense of Sachs (1893) the morphological period is regained 

 from the physiological-biological pt-riod. He (1880-1882) was the 

 first who elaborated the idea that the specific substance are concerned 

 to the development of tlie various organs of the plant from the bud. 

 Errera (1904) and Keeble (1910) also suggested the presence of such 

 substances in the specific relations held by the growth and development 

 of different parts of the plant. Recently LoEB (1916, 1918) developed 

 the idea by the study of regeneration in Bryophyllum Calvcinum. 



Granted that the specific substance, hormone or chemical co-ordi- 

 nation is the basis of correlation of the sex control in the prothallia, 

 there mav be such substances as antheridia-producing and archegonia- 

 producing substances. Coulter (1914-) thinks that the sex determiners 

 are " conceived of as representing substances that under appropriate 

 conditions react in such a wa\^ as to determine the appearance and 



