386 Transactions. 



Art. XLIV. — Further Studies on the Prothallus, Embryo, and Young 



Sporophyte of Tmesipteris. 



By the Rev. J. E. Holloway, D.Sc, F.N.Z.Inst., Hutton Memorial 



Medallist. 



Read before the Philosophical Institute of Canterbury, 1st December, 1920 ; received by 

 Editor, 31st December, 1920 ; issued separately, 12th August, 1921.] 



Plate LXIII. 



Introductory. 



The first accounts of the prothallus of Tmesipteris to be published were 

 those contained in the two papers of Professor A. A. Lawson (11, 12), in the 

 latter of which the author also described the prothallus of Psilotum. In 

 the same year Darnell-Smith (3) published an account of the prothallus of 

 Psilotum, and described his successful attempts to germinate the spores 

 experimentally. Lawson's two accounts relate to the mature prothallus 

 and sexual organs of both Tmesipteris and Psilotum, there being shown to be 

 a more or less close resemblance between the two plants with regard to the 

 gametophyte generation. A single embryo of Tmesipteris was figured also 

 in his first paper. 



In the following year I published an account (7) of the prothallus and 

 young plant of Tmesipteris, based on abundant material obtained in the wet 

 forests of Wostland, New Zealand. The development of the sexual organs 

 and of the embryo was described, but in the case of the latter the series 

 obtained was incomplete, although it indicated the absence of root, suspensor, 

 and cotyledon. The main object of the present paper is to trace more 

 fully the development of the embryo and of the young plant. The absence 

 of a root organ from the adult plant, and its probable absence also from the 

 embryo, together with the discovery of the rootless Rhynie plant fossils 

 in the Scottish Early Devonian (8. 9, 10), gives to the Tmesipteris embryo 

 and young plant an exceptional interest. Although the series of embryos 

 studied for the purpose of the present paper is still not altogether complete, 

 the results obtained seem to be such as to warrant immediate publication. 



The new material on which this account is based has, as before, all been 

 obtained in Westland. It embraces about seven hundred prothalli in all, 

 many of which bore embryos of different ages and attached plantlets, and 

 also a full series of detached plantlets. 



It may be mentioned that the embedding in paraffin was practically all 

 done at home by the aid of the simple brass table illustrated by Chamberlain 

 on page 14 of the third edition of his Methods in Plant Histology (Chicago, 

 1915), the results obtained being cpiite satisfactory. The stain used 

 throughout was Delafield's haematoxylin, this being chosen on account of 

 its clear differentiation of embryos. In some cases safranin was used in 

 conjunction with it. The drawings were made with the aid of a Leitz camera 

 lucida. I have to thank Dr. Charles Chilton, of the Canterbury College 

 Biological Laboratory, for permission to work in the laboratory from time 

 to time, and for his interest in my work. 



