INDUCED APOGAMY 



may have been, present in some cases, though of a kind quite unlike those operative in 

 the cases of direct apogamy previously discussed. 



List of results obtained by Lang in 1898 



Name Form of apogamy 



Scolopendrium vulgare Sm. var. ramulosissi- Cylindrical process usually from the apical region of the prothallus. 

 mum VVoll. Tracheids in cylindrical process. Leaves, roots, sporangia and 



ramenta on process. Vegetative buds from tip of cylindrical process 

 or in place of an archegonial projection. 

 var. marginale Similar to var. ramulosissimum but no sporangia, ramenta or leaves found. 



JVephrodiu'm dilatatum Desv. {— Dryopteris Cylindrical process usually from the under surface just behind the apex 

 dilatata) var. cristatum gracile which formed a middle lobe. Tracheids in process and middle lobe. 



Sporangia sometimes associated with ramenta on middle lobe and 

 process. No vegetative buds. 



jV. Or^o/)fem Desv. (var. coro«a;;5 Barnes) Cylindrical process from apex of prothallus. Tracheids in process. 



Ramenta on process. Vegetative buds rare. 



Aspidium aculeatum Sw. ( = Polystichum acu- Tracheids in prothallus. Vegetative buds rare. 

 leatum) var. multifidum W'oU. 



A. angulareWiVid. {= Polystichum angulare) Ramenta on prothallus. Vegetative buds frequent, 

 var. foliosum multifidum 



No apogamy seen. 



var. acutifolium multifidum 



Athyrium niponicum Mett. 

 var. cristatum 



A. Filix-femina Bemh. var. percristatum 

 var. cruciato-cris latum 

 var. coronatum Lowe 



Polypodium vulgare L. var. grandiceps Fox. 



Aspidium frondosum Lowe 



Tracheids in prothalloid growths from archegonial projections. 

 Similar to normal form but in addition a few apogamously produced 

 vegetative buds. 



Cylindrical process from apex or under surface. 



Tracheids in process. 



Continuation of process as a leaf. Vegetative buds. 



Isolated leaflike growths. Vegetative buds numerous. 



Vegetative buds on short cylindrical processes. 



In addition to Lang's paper of 1898 the earlier Hterature includes observations by 

 Stange (1887) and Heim (1896), both containing observations on apogamy in species of 

 Doodia. Helm's paper is of particular importance as the first description of cyhndrical 

 processes in D. caudata. Later, in 1908, Yamanouchi described some early stages of 

 apogamy without cylindrical processes in 'Nephrodium molle\ but doubt was cast on his 

 results by Black in 1909, who attempted to repeat them but failed. Later still, in 1929, 

 Lang returned to the study of sporangia on prothalU through a repetition of the pheno- 

 menon in new material and gave some additional descriptive facts about it and about 

 apogamy as a whole in Scolopendrium. Lastly Duncan, working under Lang's direction, 

 repeated Helm's early work on Doodia caudata, adding some important new facts to it 

 (Duncan, 1941). These included, for the first time, some cytological observations on 

 apogamously produced plants, the two chromosome numbers found being given by 

 Duncan as c. 65 and c. 130 respectively. This confirms the reaUty of the fact of induced 

 apogamy, if confirmation were needed, and it also adds the last paper of importance to 

 the subject with which I am acquainted. 



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