172 Shiv Ram Kashyap. — The Structure and Development of 
Sexual Organs. 
Archegonia. The prothallus invariably forms archegonia first, the 
antheridia being formed only on older female prothalli. Out of several 
hundred prothalli of all ages which were examined not one was a pure male, 
but most were female and others bore antheridia in addition to archegonia. 
The antheridia, moreover, are formed very late in the year. 
Archegonia were found on prothalli less than 1 millimetre in diameter. 
They are formed as usual at the base of the lobes, but all the lobes may not 
bear them. They are formed in very large numbers and may be 200 or 
more in vigorous prothalli. The early stages are difficult to follow satisfac- 
torily, as the development is very rapid and the cells in young archegonia 
do not differ from the ordinary cells of the prothallus. In the mature 
archegonium the neck projects freely and consists of four rows of cells, each 
row in the free part consisting of two or three cells. The terminal cells are 
very long, and on maturity become brownish and bend strongly outward 
after separating from each other. The most interesting feature in the 
archegonium, however, is that there is a single neck-canal cell, and not two 
cells as is the case in other species of Equisetum . The ventral canal-cell is 
small with only a little cytoplasm round the nucleus. The egg at this stage is 
concave or flat above. Later the canal-cells become disorganized, and if 
the archegonium is not fertilized the egg also shares their fate and becomes 
brown, but if fertilized the egg becomes enlarged and rounded. No embryo 
was found on any prothallus before the end of December. Thus all the 
archegonia produced before that time were never fertilized and the prothalli 
continued to increase in size. The fact that all these archegonia were barren 
is explained when it is mentioned that no antheridia were found before 
December. Figs. 28-30 show the structure of the archegonium. 
Antheridia. The antheridia are usually formed on prothalli which 
have been growing for months and are therefore large. Occasionally, how- 
ever, they occur on small prothalli which have produced comparatively few 
archegonia, but in no case antheridia alone were found. They are produced 
at the margin by the meristem and are always embedded. They are not 
formed along the whole of the margin continuously (Figs. 20, 21). On 
account of the greater lateral development as compared with radial growth 
when antheridia are being formed the margins generally become folded. 
As a rule the formation of lobes is stopped, but this is not invariably the case. 
Fig. 33 shows an antheridium at the base of a lobe. Even when no large 
lobes are formed between the antheridia, they are represented by short 
filaments as shown in Fig. 32. The position, general arrangement of 
antheridia, and the presence of ‘paraphyses’ are points which strikingly 
recall the figures of the same objects in the prothallus of Lycopodium clava- 
tum as given by Lang and Bruchmann. The paraphyses contain chloroplasts. 
