the Prothallus of Equisetiim debile , Roxb. 
179 
Concluding Remarks. 
The prothallus of Equisetum debile is remarkable in the following 
features : 
1. The great diversity in the methods of the formation of the walls in 
the early stages. Particularly interesting is the occasional occurrence of a 
‘ primary tubercle ’, comparable to that of Lycopodium cernuum (Lotsy — ■ 
after Treub — figures on p. 415 of volume ii) (Figs. 3, 7). 
2. The lobes are always erect and very close together in prothalli 
found in nature. Even when the amount of light is very small, as inside 
a room in a dark corner, the lobes are still erect. It has been remarked 
(Campbell, p. 446) that the ‘more or less upright position assumed by the 
prothallus of Equisetum is due to the amount of light ’. This does not 
hold good for the species under consideration. 
3. The radial symmetry of the prothallus from the earliest stages 
(Figs. 5, 6 , 1 6 b, 18, &c.). Jeffrey has already compared the prothallus of 
Equisetum to that of Lycopodium cernuum (Campbell, p. 446) ; but Goebel 
has remarked that there is this fundamental difference that the prothallus 
of Equisetum is not radial but dorsiventral (‘ Organography,’ Part II, p. 195) 
This objection, however, is not applicable to the prothallus of Equisetum 
debile. Even in the older prothalli the radial symmetry is very well seen, as 
in Fig. 44, where the plants are formed by the prothallus all along the 
circular margin. The chief difference which strikes the writer is that in the 
prothallus under discussion the lower compact portion is very small com- 
pared with the same portion in the prothallus of L. cernuum. When 
we consider the great diversity of form in the prothalli of various species 
of Lycopodium (Lang, Bruchmann) the difference does not seem to be very 
great. At the same time we must remember that the prothallus of 
Lycopoditim cernuum is mycorrhizal and the great development of the 
compact portion is connected with the action of the external agent. 
4. The large size of the mature prothallus. The latter is much larger 
than the largest specimens figured by Buchtien and Goebel. 
5. The changes which the prothallus exhibits in the structure and colour 
of the upper half in relation to light, being very compact and red in bright 
light (direct sunlight) and spongy and green in shade. 
6 . The absence of purely male prothalli. 
7. The protogynous condition of the prothallus, helping in cross 
fertilization. All female prothalli, however, do not produce antheridia. 
8. In position, general structure, and possession of ‘ paraphyses ’ the 
antheridia resemble those of Lycopodium (cf. Figs. 20, 2T, 31-33 of this 
paper, with Figs. 3 and 9 of Lang’s paper, and Figs. 14 and 28 of 
Bruchmann’s paper). 
