290 On the ProtliaUmm of Phylloglossum. 



1. The spike or strobilus occasionally branches ; perhaps one stro- 

 bilus in two thousand will be found forked, the two divisions becoming 

 equally developed. I am of course only speaking of the form which grows 

 in New Zealand, and this may possibly be a slightly more robust form 

 than that found in Australia. The branching always takes place above 

 the lowest sporophyll, sometimes quite at the base of the spike, near 

 the lowest leaf, sometimes further up, or even close to the apex of the 

 strobilus. 



But even when the strobilus forks there is no transition of form 

 between the sporophyll and protophyll. I have occasionally observed 

 on the peduncle a leaf some distance below the rest of the strobilus, 

 but such a leaf has always been of the sporophyll type. In the 

 Australian form, investigated respectively by Bower and Bertrand, to 

 whom we are indebted for most of our knowledge of Phylloglossum, 

 eight was the largest number of protophylls found on a plant, whilst 

 Bertrand urges on anatomical grounds that six is the normal number 

 of protophylls. I have collected plants with twenty protophylls, 

 whilst others with ten to fifteen such leaves are of common occurrence. 

 But even in plants richest in protophylls no transition occurs between 

 protophylls and sporophylls. So far as any evidence here available 

 goes, it would almost seem as if the two structures were not strictly 

 homologous. 



To express my meaning in the language of a modern theory the 

 protophylls may have arisen from the differentiation of the lower 

 region of a sporogonium (or the homologue of a sporogonium) in 

 which this region had already acquired sterilised tissues, whilst the 

 sporophylls arose from the upper fertile region of the sporogonium. 

 If so, the protophylls cannot be regarded as sterilised sporophylls. 



There appears to be no necessary connection between the number of 

 protophylls and the reproduction by spores. Plants with two proto- 

 phylls only may produce a weak spike, whilst plants of twenty proto- 

 phylls may be barren. 



2. In barren plants the new tuber is formed by the lowering of the 

 apex of the stem, but in fertile plants a new outgrowth is formed, 

 which Bower regards as adventitious. This may doubtless be con- 

 sidered as a form of branching. Neither Bertrand nor Bower observed 

 more than a single new tuber formed in the examples at their disposal. 

 Bower, indeed, was inclined to infer that as no other mode of vegetative 

 reproduction was known, the plant depended for its multiplication 

 solely upon the germination of the spores. But I have found that the 

 formation of two new tubers is quite a common occurrence, though 

 plants which form a single tuber are still in the majority. The two 

 new tubers may be formed on opposite sides of the plant, in which case 

 a slight dispersion of the plants takes place. Sometimes the two tubers 

 arise close together. Apparently they may be formed almost simul^ 



